MacLeod's old compatriot Hugh Fitzcairn comes to town bearing a mystery -- some of their other Immortal friends have disappeared suspiciously. MacLeod realizes that someone may be following Fitz, and realizes too late that Fitz has put Darius in danger by visiting him. Finding Darius dead in his chapel and Fitzcairn kidnaped, MacLeod won't rest until he finds the men responsible. Tracking the killers of his old friend, MacLeod discovers that there is a band of mortals hunting Immortals, and even holy ground is no protection from them. MacLeod finds the renegades in time to save Fitzcairn and confront James Horton, leader of the Hunters, but Horton eludes his grasp.

Determined to investigate the death of his old friend Darius, MacLeod follows a lead back to his old stomping grounds in the Pacific Northwest. He meets Joe Dawson, a bookstore owner with a secret; he soon learns that Dawson is a high-ranking member of an ancient secret organization known as The Watchers, who observe and record the lives of the Immortals, passing their archives down from generation to generation. Unbeknownst to Dawson, his brother-in-law, James Horton (the man who killed Darius), has been recruiting Watchers to kill Immortals. We are left with the knowledge that other renegade Watchers may be waiting to try for MacLeod's head.

A mortal named Pallin Wolf, one of the renegade Watchers who believes the Immortals must be eliminated, lures an Immortal to his house and kills him, getting the advantage by tricking him into a sealed room that is completely dark, then stalking him with night vision goggles. Meanwhile, a Gypsy fortuneteller they meet in a restaurant, Greta, warns Tessa that she is in danger. When Tessa is kidnapped by Wolf, MacLeod returns to Greta, asking for her help. But she's mostly a hustler, and not accustomed to getting actual visions, so the clues she is able to provide are meager. Finally, Mac finds Wolf's house, where Wolf is waiting for him. He meets Wolf in the dark room and all seems hopeless until he remembers a matchbook Greta gave him with her phone number in it. Lighting the matches, he regains the advantage and kills Wolf. However, as Tessa and Richie are heading for the car, a young junkie accosts them for money, and in an act of senseless violence, shoots them both. As Mac mourns,

Xavier St. Cloud returns, killing Immortals with the help of mortal mercenaries who shoot his prey, making his kill easy. His next target is MacLeod but, warned by Dawson, Mac and Charlie just manage to escape death -- though the dojo is all but destroyed in the gunfight. Renee Delaney, a CID agent investigating the mercenary angle, gets on the case. MacLeod goes after Xavier himself, and Charlie insists on coming along. During his battle with St. Cloud, MacLeod spots James Horton, the Hunter who killed Darius. Distracted, Mac is 'killed' and falls down an elevator shaft out of beheading range, and Charlie is badly wounded and lies near death. Blaming Dawson for helping Horton escape alive, MacLeod warns him not to cross his path again.

As Charlie regains strength, MacLeod accepts help from Dawson one last time, and barely misses catching Xavier and Horton. He then follows their trail to Paris -- accompanied by the persistent Renee Delaney. They track down Horton, and when he almost escapes, he is shot by Joe Dawson. MacLeod, with the help of his humorous new neighbor Maurice, then tracks down Xavier and finally takes his head. In a coda, however, we learn that Horton still lives.

After Midori Koto sees her husband, rich industrialist Michael Kent, murder her lover, she kills Kent and runs to MacLeod for protection. She reminds MacLeod of a vow of protection his ""ancestor"" (actually MacLeod himself) made to her family over 200 years before. Flashbacks tell the story of MacLeod coming to the aid of the samurai Hideo Koto after MacLeod is shipwrecked in Japan. Hideo befriends MacLeod -- even though the penalty for helping a ""barbarian"" in isolationist Japan is death. When Hideo is forced to commit ritual hari kari by his feudal overlord for that crime, MacLeod serves as his second. He vows to Hideo he will always protect the Koto family and is bequeathed the dragon head katana sword he uses to this day. Back in the present, MacLeod discovers that Kent is an Immortal and he's still alive. In order not to further dishonor her family's name, Midori returns to Kent. Kent challenges MacLeod, who fulfills his vow to the Koto family and frees Midori from her loveless mar

In the 1600s, MacLeod sought refuge for a time in a monastery founded by Paul, another Immortal. There he encountered Kalas, an Immortal monk with a heavenly singing voice. When MacLeod discovered that Kalas was routinely taking the heads of Immortals as they left the sanctuary, MacLeod and Paul expelled Kalas from the monastery, separating him from the music that was his life. Now in the present, Paul and his choir have been lured out of their monastery for a concert tour. When Paul disappears after a concert, MacLeod discovers that Kalas is after his revenge. Meanwhile, two mysterious deaths at the hospital seem to be linked to negligence on Anne's part. Later, when drugs are found in Joe's bar, it becomes obvious that Kalas is trying to destroy MacLeod's friends before coming for him. MacLeod confronts Kalas and finds that Kalas is a strong and skillful fighter, better than MacLeod has faced before, and is nearly the victor. To save himself, MacLeod throws himself off the concert ha

MacLeod is picked up at the airport in France by his old friend, Hugh Fitzcairn. For the first time in the 350 years MacLeod has known him. Fitz has settled down as a Universitv Professor with the love of his life, Naomi. Flashbacks show MacLeod and Fitz's first meeting, when MacLeod was protecting the Doge's daughter from Fitz's amourous advances in Venice, 1637. When Naomi's jealous ex-lover is found strangled next to a computer displaying Fitz's falsified teaching credentials, Fitz goes on the run from the police. MacLeod realizes that Fitz is being framed by Kalas, who has followed him from the U.S. Kalas challenges Fitz and takes his head while MacLeod watches, unable to interfere.

When two Watchers end up dead by Kalas' hand, Joe realizes that Kalas is looking for Methos, the mythical ""oldest Immortal."" MacLeod knows that, with Methos' quickening, Kalas would finally be strong enough to defeat him. Kalas and MacLeod race to be the first to find Methos. Meanwhile, Richie muscles his way onto a top level motorcycle racing team and the champion, Basil, starts to get nervous. Flashbacks are to Paris in the 1920s, when Kalas, then known as Antonio Neri, was the toast of the opera world. When Kalas threatens a young girl in MacLeod's protection, they fight. Kalas escapes, but not before MacLeod inflicts a throat wound that destroys Kalas' vocal chords and the singing that has been his life since the Middle Ages. Kalas nearly takes Methos in battle and, realizing that he will not be able to defeat Kalas, Methos offers his own head to MacLeod. MacLeod refuses and challenges Kalas on his own, nearly defeating him when the police arrive to send Kalas to prison for the dea

McLoud bought a Celtic bracelet once given to the love of his mortal life and after her tragic death he buried it with her. He returns to Glen Finnin to return the bracelet to her grave and learns of several gruesome ritualistic killings based around the one immortal who killed Mac's father. Naturally Mac must get to the bottom of the killings and keep his head in the process.

MacLeod knew him as Melvin Koren, a desperado who left a trail of death and fire across the Old West, but Cassandra remembers him as an evil far older. He is Kronos, leader of the Four Horsemen, mounted Bronze Age raiders who murdered, raped, and pillaged their way across two continents. Never was a band of Immortals more cruel or more feared. He destroyed Cassandra's people and she's been hunting him across the millenia. But Kronos has a different target now -- Methos.

In 1944, Ingrid Henning had the chance to kill Adolf Hitler and failed. She's been atoning for that failure ever since by killing dictators, tyrants, racists, and fascists who might have the potential to become as dangerous. MacLeod has a chance to stop her before she kills more mortals, but by stopping her, does MacLeod commit the same evil for which he's judged her guilty?

When MacLeod was but a wee lad in the village of Glenfinnan, he thought Cassandra, the Witch of Donan Woods, was only a myth, a fairy tale concocted by crafty old men to frighten unwary children-- until the night she found him alone in Donan Woods. Now, four hundred years later, Cassandra comes to MacLeod again, this time to tell him of his role in an ancient prophecy -- that only Duncan MacLeod can challenge and defeat the voice of darkness.

A serial killer dubbed The Scalper' is attacking blonde women, including a friend of Tessa's. MacLeod recognizes the pattern of an Immortal who, betrayed by the woman he loved, became a killer. To end the carnage, MacLeod was forced to confront and kill him, back in 1925. Now the killings have started again, the modern day killer mimicking the 70-year-old M.O., killing in the same locations as the previous murders. It falls to MacLeod and Tessa to stop this madman.

An Evil Immortal, Kuyler, has hired himself out down through time as an assassin -- the most successful killer in all of history. He strikes again in modern day Paris using his signature disguise as a mime. A French Police Detective, LeBrun, suspects that Duncan MacLeod is connected to Kuyler, but of course he cannot imagine that Kuyler once killed an eighteenth-century baron under MacLeod's protection. When LeBrun is wounded protecting Tessa from Kuyler's men, MacLeod confronts the Immortal assassin and puts an end to his centuries-old reign of terror.

MacLeod stumbles across the trail of an Immortal, Xavier St. Cloud, who has lived in hedonistic splendor down through the ages by remorseless robbing and killing innocent men and women. MacLeod had nearly fallen victim to this remorseless killer behind the front lines during World War One, when Xavier used poison gas to loot a payroll truck. He uses even deadlier gas in modern day Paris, and MacLeod must track him down before he kills again. He succeeds in defeating Xavier, but the Evil Immortal escapes with his head. In a humorous yet touching subplot, Richie falls for a glamorous older woman, not realizing she is married, and Tessa must disentangle him from the woman's clutches.

A mysterious death at the Paris Opera re-acquaints Duncan MacLeod with one of the strangest Immortals he has met in his many travels over the centuries. Ursa is a hulking giant -- more beast than man -- who Duncan rescued from persecution centuries ago, delivering him to sanctuary in an abbey. The abbey has long since been destroyed and Ursa now lives under Paris. He has become enamored of a past-her-prime opera singer who tries to use Ursa's innocent soul to murder her rival.

Grace Chandel has been a Good Immortal, working for the betterment of mankind as a midwife, doctor, and scientist over the centuries. Her one weakness is another Immortal, Carlo Sendaro, a former lover who is obsessed with her and refuses to let her go. He slays Grace's current (mortal) lover and, when she refuses to run off with him, frames her for the killing. She turns to her old friend Duncan MacLeod for help.

A day at the circus reunites MacLeod with a former lover, the Immortal femme-fatale, Amanda, who has always meant big trouble for him. Amanda, meanwhile, is in trouble of her own as her former partner, Blaine, has escaped from prison and wants her head. She plays the two Immortal men against each other, drawing MacLeod into a daring, high-stakes burglary she and Blaine are plotting.

Richie meets a beautiful young woman who leads him into the world of haute couture. His youthful jealousy causes him to run afoul of a world-class fashion designer, a deadly Immortal.

When fatal stabbing fails to kill him, Alfred Cahill becomes convinced that he has been chosen by a higher power to wage a crusade against 'perversion', and cuts a bloody path through Paris, murdering prostitutes and pimps, and endangering an old friend of Tessa's who has become a call girl. MacLeod tries to explain Immortality to Cahill, but he can't get through to him, and finally is forced to take his head.

When the stepdaughter of an Immortal is raped, the Immortal comes after the young man. MacLeod, a guest in the home of the accused boy's father, feels he must protect the family from this unstoppable menace. He urges the Immortal to see due process done, but the man has no interest in listening to reason, and he lays siege to the house.

A fellow Immortal, Greg Powers, invites MacLeod to his photography showing. At the gallery, MacLeod becomes deeply disturbed by the violent images of his friend's work, but what becomes more disturbing than the fact that Greg's personality has been replaced by that of a hardened cynic. As he reviews Greg's work, he comes across a photograph taken of himself 50 years ago which triggers a flashback of a time he spent with a young photographer, Linda Plager. In a chance meeting, the now 73 year old Linda recognizes Duncan as her old mentor and lover of 50 years ago, which thoroughly convinces her nurse that she's senile. Upon learning that Linda is dying, MacLeod longs to tell her the truth. Meanwhile, Greg seduces Richie into his destructive lifestyle and coaxes Richie into a dangerous motorcycle stunt. After a confrontation with Macleod, Greg snaps...frustrated by his inability to feel any real emotion because of the insulation from death his immortality gives him, he attacks Richie, an

Thirty years ago, evil Immortal Quenten Barnes was executed in the electric chair, and promised he'd be back. Escaping the tomb that he has been captive to for the last several decades, Barnes begins hunting down the people involved in his execution. Joe Dawson learns that he has returned and tries to get MacLeod involved in Barnes' apprehension. Mac declines to get involved unless Barnes gets in his way, but when his old friend Michael Moore comes to town, a flashback shows us that Barnes killed Michael's wife and has a long-standing grudge against Michael. Now Mac is involved. He convinces Dawson to share the Watchers' surveillance file on Barnes with him. However, the file isn't much help. As the prosecutor and priest who were at Barnes' execution are killed off one by one, it becomes clear that Barnes will come after Michael next. The story ends with an interesting twist as MacLeod must make a decision that will affect the ""lives"" of two different personalities.

When MacLeod and Richie are witness to a terrorist attack on an Ambassador, Richie dives in like a Superhero, cocky with Immortality. In the resulting confusion, one of the terrorists is killed, and another, Annie Devlin, an Immortal, is captured. She swears revenge on Richie, and when she escapes from custody, MacLeod takes on the task of educating Richie so that he will have a chance in combat against her. Meanwhile, Flashbacks reveal an earlier friendship between MacLeod and Annie. Mac renews the friendship, and the two Immortals who have both recently lost their lovers find solace in one another. In the end, Richie defeats Annie but can't bring himself to kill her, and MacLeod convinces her to pursue the blood debt no further.