After Ken Lydecker fires a salesman, Hollis, Hollis wires himself with a bomb, goes back to the office, and takes everyone hostage. The police negotiator convinces Hollis to release everyone except Lydecker, who Hollis has tied up and hooded. After the other hostages have left, Lydecker asks if Hollis done... but the voice isn't Lydecker's. The real Lydecker is outside, safe.
The man standing in slips out of his bonds and stands up: it's Christopher Chance. He points out that Hollis made threats instead of taking action, giving Lydecker enough warning that he hired Chance. Hollis insists that Lydecker deserves to die because he fired him, but Chance notes that no one deserves to die. He advances on Hollis, who is so surprised that he forgets to fire. Chance disarms him and Hollis takes out the activator for the belt of explosives that he's wearing. Chance asks if he really wants to blow himself up, and Hollis announces that he plans to run outside and get as close to Lydecker as possible, and then take him and everyone else out. Chance points out that Hollis is again making threats instead of taking action, and fires a single shot at the explosives belt.
Outside, the police and the hostages duck back as the building blows up.
Four Weeks Later
Chance is checking his injuries at his loft apartment and office when his partner Winston comes in. Winston is less than thrilled that Chance accepted a 25-year-old bottle of Japanese whiskey in payment, but Chance insists it'll appreciate in value. Winston wonders why Chance didn't disarm Hollis when he had the chance much earlier in the situation, but Chance insists that he knew that the retaining walls would contain the blast and the fuse delay would give him three seconds to get to cover. Winston goes to meet their contact in the San Francisco police, Lt. Peale, who has a new case for them. He tells Chance to stay put and recover from his injuries and let him deal with new clients.
The prospective clients are Stephanie and James Dobbs. Stephanie explains that someone has targeted her for assassination, and planted an explosive in her car. Thanks to her car mechanic, she found it before it was set off. Peale admits that the police aren't authorizing necessary protection. When Winston wonders what Stephanie does, she explains that she's the chief engineer for McNamara Engineering in charge of the Montery Line, the first American bullet train. It's launching shortly and Stephanie wants to hire Chance to flush out the killer so she doesn't have to live in fear. Chance comes in over Winston's objection that they're not taking new clients. Once Chance confirms that the train goes 200 miles an hour and he'll get to ride on it, he agrees to take Stephanie's case.
On the day of the launch, Stephanie arrives at the station and Chance goes undercover as her translator for the Japanese executives. Much to Stephanie's surprise, Chance speaks perfect Japanese and impresses the executives. Afterward, she asks him how he learned Japanese and he tells her about his grandfather who befriended a steward... and then admits the entire story is a fabrication. As they board, Chance explains that he'll be able to deal with the killer in a confined space with no escape, and that in three hours the issue will be resolved, one way or another.
The bullet train leaves the station and heads for Los Angeles. Chat talks with Tom, James' co-counsel. Tom warns that Stephanie is a lousy boss but she keeps her job because her husband runs interference for her. Chance steals Stephanie's phone and calls Winston, and has him check the phone logs to see if Stephanie is hiding anything. He also tells Winston to bring in Guerrero to check the corporation records. Winston doesn't want Guerrero involved but Chance figures they can trust Guerrero as long as they pay him. As they talk, Chance notices a man watching Stephanie and fingering something in his pocket.
Guerrero is at a diner when two thugs come to see him. They try to warn him off the investigation of their employer, a bank director who is making shady loans. When Guerrero refuses to back off, they offer to take him out back and beat him. He agrees, but warns them that later he'll hunt them down and kill them in their sleep. They hastily back off as Guerrero takes a call.
Winston calls Chance back to confirm that he's hired Guerrero for the job. He passes on that Stpehanie's phone logs show she received a number of calls from Mark Hoffer, a Sacramento reporter. Stephanie sits down and realizes that Chance stole her phone. The man who was watching Stephanie comes over, but introduces himself as Bill Arnold and says he's there to apologize for opposing her project. As they talk, a steward brings Stephanie a glass. Chance notices that the ice cubes in her glass are a different shape from everyone else's. He quickly gets her away and Arnold inadvertently drinks from her glass. As Chance gets Stephanie out of the reception car, Arnold clutches at his throat and collapses. He gets her into an empty car and tries to bar the door, and figures that the killer will come after them since the poison attempt failed.
A Sacramento newspaper editor, Lowell, gets into his car and discovers Guerrero waiting for him. Guerrero asks for information on Hoffer and Lowell reveals that the reporter is dead. Guerrero calls to tell Chance that Hoffer was killed in a car bomb explosion, the same type of bomb on Stephanie's car. Chance confronts Stephanie with the news and she finally admits that Hoffer was investigating improprietaries at McNamara. They cut back on safety features, and Stephanie secretly blew the whistle on them to Hoffer because she didn't have any other choice. Once Hoffer published his story, McNamara properly financed the safety features. Chance figures she's hiding something else but Stephanie claims that's the only secret she has. As they talk, Stephanie hesitates and then says that she can hear the brakes squealing.
Someone comes through the door and Chance grabs the man when he comes upstairs. It's Tom, who tells them that Arnold is hanging by a thread and may not make it to L.A. He wonders why Stephanie pulled the emergency brakes in the last car, and she says that she didn't. Chance sends Tom back to the reception car.
Winston finds Guerrero using his computer at the office to check Hoffer's hard drive. He insists that Guerrero will be gone when the mission is over, but Guerrero ignores him. When Chance calls to tell them what Stephanie told him, Guerrero leaves to see if he can find something on the streets about McNamara Corporation.
On the train, Stephanie speculates that the killer panicked and pulled all of the emergency breaks. However, not all of the batteries are hooked into the computer and triggering them all at once overwhelmed the computer control system. If the emergency brakes are engaged again, they'll blow out. Also, there's a curve coming up on the route and they'll have to engage the brakes to slow down. The steward from the reception comes in and opens fire. Chance leaps in front of Stephanie, taking two bullets in the back before collapsing on her. As the killer comes in, Chance comes back to life and opens fire. They flee through the cars and Chance tries to block the door, and then takes off his bulletproof vest. They discover that they left their phones in the empty car and have no way to call for help.
Guerrero meets with an old friend, who informs him that McNamara isn't hiring any criminal talent. As Guerrero leaves, the man notes that Guerrero may have switched sides, but he's not well suited to it like Chance is.
Chance and Stephanie get into the ductwork and try to crawl to the next car. Chance removes the grate only to discover the killer trying to get at them via the ductwork. He crawls forward and grabs the guy before he can draw his gun. The two men struggle until the ductwork breaks and they drop to the floor below. Chance finally manages to shatter a window, and then kicks the killer through where he falls to his death.
Chance gets Stephanie back to the reception car and they explain what's going on. The CEO, McNamara, says they've already engaged the brakes and there's nothing to worry about. The brakes blow out and everyone realizes that they're in trouble. Stephanie suggests that everyone get to the rear car and then she'll engage the supplemental brake system. The train will slow down enough that if they disconnect the last car with all the passengers, it will fall behind and ensure their safety.
Guerrero goes back to the office and has Winston pull up the phone log information from Stephanie's phone. Winston does so and realizes what the information means. However, he's unable to get hold of Chance on his cell phone.
Stephanie insists she's the only one who can engage the supplemental breaks and tells James and the others to go without her. Chance stays with her and she succeeds, but when they get to the car door, they discover someone has tied it shut with a necktie. Chance breaks the door down but it's too late: the last car has detached and has drifted too far back for them to jump.
With time running out, Chance rigs up a drag chute from seat belts and cargo tarps. He tells Stephanie that it'll be fun, grabs her, and tosses the tarp out through the door. It catches the wind and pulls them to safety as the train crashes at the curve.
Back at the station, James assures Stephanie that it's time to come home. However, as the couple leaves, James gets a call. It's Guerrero, who informs him that Hoffer and Stephanie were having an affair and all of the calls to Stephanie came from the same hotel, one year ago. James rounds a corner and finds Guerrero and Chance waiting for him. Chance reveals that he recovered the tie from the train, and it's the necktie that James is now missing. Stephanie tells James that her affair was over a year ago, but Chance explains that James waited a year so he could collect the bonus she'd get for completing the Monterey Line on time. Stephanie slaps her husband and walks, brushing past Chance.
Later, Chance meets with Stephanie, who admits he was right for suspecting she was hiding something. Chance says that feeling regret is no reason for people to die. Stephanie says she doesn't know how much she owes him, and Chance takes her hand and removes her diamond wedding room. As he takes it as payment and leaves, Stephanie asks what his name really is. Chance just smiles and walks away.
Later, Winston pays off Guerrero and insists he won't be coming back. Chance says that they'll need him again. Winston wonders if Chance is taking on dangerous assignments to try and get himself killed, but Chance insists that he hasn't lost his focus. Winston isn't convinced.
One Month Later
Chance is posing as a chauffeur for a rich businessman, his newest client. Thugs cut them off in an alleyway and Chance asks his client to get him the bottle of Japanese whiskey he has in a bag in the back. Chance takes a drink and explains that once he would have saved it, but now he plans to enjoy things in the present. When the customer wonders if he's crazy, Chance lights up the whiskey bottle, gets out to throw it at their attackers, and suggests that they find out how crazy he is.