The sole survivor of an Army plane crash in the Peruvian hinterlands, Jim Ellison subsisted for nearly two years on his raw animal instincts. When he returned to America and became a police lieutenant, Jim discovered that the abilities that had kept him alive in the jungle now gave him extraordinary senses of perception. With the help of Captain Simon Banks and a grad student Blair Sandburg, Jim now attempts to use these powers to apprehend a terrorist bomber called the Switchman.

The town of Cascade is brought to its knees when Garrett Kincaid, a notorious criminal that Jim Ellison had arrested years before, seizes control of the town's police station with the help of his gang of felons.

When Blair's mother Naomi secretly submits her son's Sentinel thesis paper to a publisher, Jim discovers that being famous can be detrimental to your health. While Jim and Blair protect a local union leader named Jack Bartley from attempts on his life, information from Blair's paper is leaked to the press and Ellison is caught in the middle of a media frenzy.

Jim and Blair are assigned to escort Derek Wilson, a key witness in a local homicide case, on his train ride from Oregon to the courthouse in Cascade. Wilson has essential information that will link his employer to charges of arson and murder.

Blair forces Jim to take a vacation at a remote monastery. Initially reluctant, Ellison begins to enjoy the solitude until one of the monks is found dead.

Visiting his cousin Rucker on a remote island, Jim learns that people on deserted islands don't always pursue the "natural life." While rescuing a woman named Monique from a storm-tossed boat, a huge bag of heroin surfaces.

During a flight to South America, Captain Banks and his son Daryl crash land in the Peruvian jungle and eventually stumble across a shady lumbering operation run by a man named Reischer.

After a minor car accident and heated argument with the driver, Dan Freeman, Jim Ellison finds that this unbalanced man has targeted him for a full-blown vendetta.

Blair, Banks, and Megan may be Jim's only hope of overcoming the superhuman stalemate and returning Cascade to a one sentinel town.

A present day murder leads to a revelation that may be able to finally clear up a 45 year old murder, and vindicate the victim and the boy (now a troubled, haunted man) who saw it happen. And Jim discovers a new ability.

When Blair unknowingly moves into an apartment next to the drug lab of a local gang (dubbed the 357), Jim suddenly finds himself embroiled in the beginnings of an all-out gang war.

While guest-lecturing in Blair's anthropology class, Jim saves the entire building from a deadly gas leak only to discover that the leak was designed to distract the campus' attention while a canister of the Ebola virus was being stolen from the hazardous materials lab.

Jim's sentinel abilities detect something strange at the crime scenes of all the recent jewelry robberies but he's unable to figure out exactly what's causing the reaction.

When Francisco Rivero, an ex-associate of Hector Carasco, kidnaps Carasco's daughter Maya and uses her as blackmail for the family fortune, Ellison and Sandburg join forces with her Uncle Gustavo to bring her safely home.

With Ellison having strange visions of jaguars and a series of superhumanly performed thefts occurring around the city, Blair and Jim suspect that he may not be the only sentinel in town.

Using his sentinel powers, Jim saves Edward, the grandson of Mafia don Dominick Lazar, from drowning. When Don Dominick himself thanks Jim for his efforts, he decides to use this opportunity to get on the inside of the city's organized crime world.

Sandburg becomes trapped between floors in a skyscraper elevator controlled by an extortionist, who threatens to send the elevator plummeting to its doom unless a hefty ransom is paid.

During the search for a kidnapped little girl, the skeptical Ellison and Sandburg receive help from Charlie Spring, a "psychic."

After witnessing the death of undercover officer Danny Choi at the hands of a sniper named Tommy Juno, Jim uses his enhanced vision to identify and apprehend the killer. But the case against Juno is thrown out of court when its decided that no human could possibly have seen as far as Ellison had claimed.

Blair and Jim, along with forensics specialist Carolyn Plummer, suspect that a series of seemingly unrelated murders are actually the work of a serial killer.

Ellison gets his fifteen minutes of fame when the police department invites TV producer Wendy Hawthorne and Conner, her cameraman, to do a piece on him for her show "True Crime."

Ellison and Sandburg are called in to investigate an attack on a prostitute named Amber Larkin.

Ellison and Sandburg get a chance to hone their driving skills when some high-end car thieves set up shop on the streets of Cascade.

Ellison and Sandburg trace the distribution of Golden, Cascade's trendy new drug, to a local dive where the narcotic wreaks havoc with Ellison's enhanced senses.

An arsonist burns down a furniture warehouse, and Ellison rescues an unconscious guard from the building.