Thanks to a leak in Chrysalis, Hobbes and Darien get the goods on a politician that Allianora is trying to bribe. Realizing they have a leak, Chrysalis takes unspecified measures to stop the leak. Allianora visits Darien and tries to force him to give up the name of their contact, but he refuses and the two end having making (invisible) love. The next morning Bobby and Darien meet with the contact, only to have him killed by a Chrysalis ambush. The Keeper soon realizes that Darien was bugged with nanobots during his...encounter with Allianora. They transmit everything he sees and hears. The Official fake-executes Darien while they put an insulated helmet on him to make Chrysalis think he's dead. They then investigate a pharmaceutical firm and discover Chrysalis plans to attach the nanobot bugging devices to students at an elite school. While Hobbes and the Keeper stop them, Darien tries to lure off the Chrysalis strike team to the school pool. Using a pair of goggles, he prevents them

Going to Mexico to investigate Arnaud, Bobby meets his new partner Bobby Hobbes: a veteran spy and near basket-case. They escape an ambush by French-Canadian spies. Meanwhile, Arnaud has had Darien's girlfriend Casey brought down to Mexico, planning on using her as a hostage. Darien goes to rescue her, prepared to kill Arnaud since Darien thinks he'll be going insane shortly. Arnaud plays his trump card: there's a counter-agent that will stave off Quicksilver madness, and he'll give it to Darien if he works for him. Darien refuses, escaping with Casey and blowing up the compound (although Arnaud escapes). Both the counteragent and the formula are destroyed, and Darien goes to visit his brother's grave one more time before going permanently insane. However, the Official meets him there and reveals that his Agency was working with Kevin, and they have the counter-agent as well. As long as Darien works for them, he'll get regular doses of the Counter-Agent. Reluctantly, Darien agrees.

Darien Fawkes is a con-man and thief who is captured for a third time. Rather then face California's three-strike law, he volunteers for an experiment conducted by his brother Kevin. Kevin and another scientist, Arnaud, have created a synthetic gland that secrets ""Quicksilver"", a substance that can bend light. They place the gland in Darien's head. He soon realizes what has happened and is none too pleased. Darien is even less happy when they discover the gland secretes Quicksilver into the recipient's brain, and enough of it drives the person insane. Darien learns to control his abilities, and soon discovers that Arnaud is up to something. Arnaud claims Darien is insane when he accuses the scientists, but then Arnaud's mercenaries break in, steal the information on the gland, and kill everyone except Darien. Darien goes to his ex-girlfriend, a doctor who is furious at him because he didn't reveal his past. She refuses to believe he can turn invisible, and then Darien is taken away by

A young girl is a witness to an assassination by a sniper. Traumatized, she only speaks to her imaginary friend ""Ralph."" Darien, using his powers of invisibility, convinces the girl he is ""Ralph"" and tries to get her to talk about the murder. Eventually the hit man tries to kill the girl, and Darien manages to stop him. With his help, the girl starts to recover from her trauma, and leaves her ""imaginary friend"" behind.

Hobbes and Darien are on the trail of a sperm thief. A college professor is using the sperm to isolate intelligence-causing genes, and put them into a retrovirus. Hobbes is accidentally infected and soon begins to become more and more intelligent. But the partners discover that the gene therapy is lethal. Bobby becomes smart enough to create a cure...but refuses to do so, preferring to die smart then live dumb. Darien infects himself, leaving Hobbes no choice but to come up with a cure to save his friend.

Alex finally locates her missing son at a Chrysalis baby camp, only to discover that he belongs to Stark, the agency’s sinister leader.

Darien is contacted by his former mentor and partner, Liz, who wants his help. She wants him to return to his thieving ways and help her steal some FBI files on a mobster who has hired her. Initially reluctant, Darien eventually grows aggravated with the Agency's treatment of him and links up with her. Covertly using his powers of invisibility, Darien manages to get hold of the files, only to realize that the mobster plans to use them to kill a government witness against him. Darien tries to thwart the mobster and keep Liz safe, and manages to do so. The two of them part on relatively friendly terms.

Darien and Hobbes learn that the Chrysalis Agency is artificially inseminating women all over the country and stealing their babies to create its own unstoppable army.

The keeper develops a way to keep Darien's invisibility static.

Darien encounters a bizarrely-aged woman and soon becomes infected with the same disease, causing him to rapidly age.

Darien comes to the aid of a female scientist who may be able to remove the Quicksilver gland.

Hobbes starts trailing his ex-wife, and gets arrested as a stalker. Hobbes believes his ex-wife Vivian's new fiance is a crook. Darien thinks he's jealous, but it turns out Hobbes is right, and they're assigned to the case. It turns out that the fiance is an undercover agent for Naval Investigations. They all team up to find the culprit in an illegal arms sale. They get captured but Darien manages to escape with his invisibility, and capture the bad guys. Hobbes is impressed with the fiance, Brock, and reconciles with Vivian.

Unable to craft their own invisiblity gland, the Chinese government sets out to steal the American one. Unfortunately, they have the idea that Bobby Hobbes is the invisible member of the team. Fawkes and Hobbes go into hiding, but Bobby gets nervous. After several chases, Hobbes apparently dies in a car crash. It's a set-up, but he turns up at his own funeral to look on from a distance, and is captured there by the Chinese. The Agency tracks him to the Chinese embassy, and Fawkes goes in to rescue him. It turns out the whole operation is a ploy to lure out the real American Invisible Man. Fawkes manages to escape with Bobby before they can drain the Quicksilver out of the gland, setting the place on fire.

A ghoulish hitman uses a laser to blind any witnesses to his killings. Fawkes and Hobbes trace him to a blind model who the killer is romantically involved in, but the assassin escapes, blinding Fawkes in the process. Since he was turning invisible when the laser hit him, the effects are temporary, and he can still see if he covers his eyes with the quicksilver formula. Unfortunately, that aggravates his growing insanity. The blind model helps him to deal with his blindness, and the two become romantically involved. Fawkes figures out that the assassin's most recent victim was merely a lure to get his real victim to the man's funeral. Fawkes, overwhelmed by Quicksilver Madness, throws the assassin to his death.

A series of bizarre killings involve murderers who have no connection to the victims. The Keeper becomes the next unwitting ""murder,"" as she is part of a insomnia-research project. The project's scientists are using the device to program their subjects to become assassins. The Keeper's sanity is threatened if she can't complete her ""assignment."" Fawkes and Hobbes eventually mange to bring in the scientists, and come up with a means to break the Keeper of the programming (by faking the death of her ""victim"") before she goes mad.

Darien goes to an acupuncturist who discovers his powers of invisibility and forces him to help her steal a set of ancient needles from a museum to treat her mentor, who is suffering from stomach cancer.

Darien and Hobbes are assigned to help investigate an auditor's relative's suicide, and run into a man who can see the future and use it to his advantage.

The Official is assault by an invisible man and Fawkes is suspected - Darien and Hobbes work to clear Darin and find the true assailant.

A strange old man who has lost the ability to experience normal sensation comes to Darien in the hopes that he can lead him to his late brother, Kevin, whom he blames for doing a horrible thing to him.

Darien helps a young woman who seems to be haunted by a strange apparition, and she is convinced it is her mother, who had disappeared mysteriously weeks before, trying to communicate with her.

The sinister head of the SWRB discovers that Gaither is still alive and storms the Agency to recapture him, kidnapping Alex and stealing all of the Keeper’s vital computer files in the process.

Hobbes and Darien meet with one of Hobbes' contacts to set a trap for their arch-enemy, Arnaud. Arnaud manages to escape Darien with the aid of a smoke canister, which turns out to contain a biological weapon. Darien is soon displaying flu-like illness symptoms, and is excreting black, contaminated Quicksilver. The Official and the Keeper send him to a military hospital...which Arnaud has already infiltrated. He plans to remove the Quicksilver Gland from Darien's skull via surgery, but the illness complicates matters. He must kidnap the Keeper to cure Darien so he can gain an uninfected Gland. Darien manages to escape and, overwhelmed by madness, almost kills Arnaud. The Keeper manages to stop him but Arnaud escapes. (Copyright 2002 Steve Crow)

The agents find themselves hunting for the legendary Sasquatch on an Indian reservation after two men have been killed there under mysterious circumstances.

Hobbes becomes irrationally violent and shoots up a post office, and his co-workers are afraid he’s lost his mind again.

The agents are sent to capture a dangerous government assassin who is said to have switched allegiances, and Darien is stunned to discover that the man may be his own father, who has been missing for decades.