On Halloween, MacGyver comes home after a mission only to discover his neighbor Milt Bozer is pounding on his electric winch. MacGyver promises to fix it later if Milt will stop now so MacGyver can get some sleep. As they talk, Milt asks if MacGyver is moving. He explains that he saw a man with a bushy mustache moving out all of MacGyver's furniture. MacGyver goes inside and discover that all of his furniture is missing. Based on the description and the last time his furniture, he figures Jack Dalton is responsible. He drives to Jack's hangar and finds all of his stuff piled in the floor by a moving truck. He also finds a puddle of blood with Jack's pilot's wings lying in it. An unseen figure drives a black hearse into the hangar and tries to run MacGyver down, then shoots out a tire on his truck before escaping.
Checking out the hangar, MacGyver discovers that the phone is off the hook. He hits redial and is connected with Haven Rest Cemetery. MacGyver goes there and spots the hearse outside of a mausoleum. The driver has disappeared and MacGyver spots Jack's pilot's hat on the mausoleum doorstep. He goes inside and finds a coffin with a pumpkin inside of it, but no Jack. Suddenly a trapdoor opens up beneath MacGyver, dropping him into a cage. A figure emerges from the shadows: Murdoc.
The assassin explains that he lured Jack away and then faked his presence to lure MacGyver to the mausoleum. MacGyver tells him to get on with whatever game he has planned, but Murdoc released him instead. The assassin explains that he decided to retire, and even had plastic surgery to remove the burn scars from his face. However, his former employers, H.I.T. (Homicide International Trust) refused to accept his retirement. When they couldn't kill Murdoc, they kidnapped his sister Ashton. When MacGyver points out that Murdoc's file shows he has no family, the assassin explains that he took great pains to conceal Ashton's connection to him, from the world in general and from Ashton as well. H.I.T. has strapped Ashton into an electric chair and sent a photo to Murdoc. The head of H.I.T., Murdoc's mentor Nicholas Helman, has included tape telling Murdoc to come to his club or Ashton will die at midnight. Murdoc asks MacGyver for help, insisting he can't do it alone. MacGyver is reluctant until Murdoc reminds him that an innocent girl is at stake. He finally agrees, but only on the conditions that Murdoc turns himself in, gives up all the evidence he has against H.I.T., and does things MacGyver's way. Murdoc has no choice but to agree.
At the Helman Club, Helman's second-in-command Sonya Chapel brings in an assassin Hank Greggs. She escorts him to an underground chamber, Death Alley, with a mock-up of a Roaring Twenties street. Helman is in a control booth above and tells Greggs that he has to get to Ashton to pass this initiation to become a H.I.T. assassin. Helman and Sonya watch as Greggs starts his test. Automated dummies open fire on him with machine guns and live ammunition. He just manages to evade them and enters the next setting, a jungle. A hidden machine gun opens fire and shoots down Greggs as he tries to cross the area. Satisfied, Helman believes that even Murdoc is no match for the deathtrap.
MacGyver disguises himself as a caterer and delivers a coffin full of candy to the club. Ozzie, the head of security, examines the coffin and confirms there's no one hiding inside. MacGyver slips way and then follows Ozzie downstairs to the billiard room. Helman orders Ozzie to dispose of Greggs' corpse. MacGyver watches Helman open the door to Death Alley with a thumbprint lock. As Ozzie takes the corpse away, Helman reminds him that the H.I.T. board members will be arriving dressed in royal flush costumes.
After Helman goes upstairs with Sonya, MacGyver slips into the room but is unable to open the door. Upstairs, Murdoc emerges from a hidden compartment in the compartment, dressed as Death. He comes downstairs to find MacGyver. The assassin wants to blow the door open using a grenade but MacGyver reminds him about his no-guns rule. Instead, MacGyver comes up with a way to get the thumbprint from the glass Helman is drinking from. He makes a mask and then goes upstairs with Murdoc. Helman goes into a private room and MacGyver and Murdoc notice the other H.I.T. board members entering one at a time, each in a royal flush costume. They spot the last member, dressed as a joker, and Murdoc gasses him into unconsciousness. They drag the man into a private office and MacGyver tells Murdoc to throw the circuit breakers at a precise time then go back to the billiard room.
As MacGyver goes to the board room, Sonya spots him and wonders why he's emerging from the office. MacGyver enters the board room and avoids speaking. Helman calls the meeting to order and the board members ask about Murdoc's status. Helman assures them that he'll be dead by midnight, but they warn him that if he fails then he'll be disposed of, permanently.
Sonya checks out the office and captures Murdoc. MacGyver is called upon to give the joker's report, but is interrupted when Sonya calls Helman to tell him that she's captured Murdoc and he has an accomplice. Helman holds MacGyver at gunpoint, but Murdoc knocks out Sonya and cuts the lights. MacGyver grabs Helman's glass and leaves, barring the door behind him. He and Murdoc go back to the billiard room. MacGyver dusts the glass with pool cue chalk then coats his thumb with wax from a burning candle. He presses the wax onto the dusted print, capturing the image and then pressing it to the scanner. The door opens and they head for Death Alley.
Sonya recovers consciousness and frees Helman and the others. The board members think that Helman has failed but he tells them to wait and turns on a TV monitor. He goes to the control booth while MacGyver and Murdoc enter Death Alley. They spot Ashton on the opposite side of the chamber. Helman brings up the lights and informs Murdoc that the chair will activate in eight minutes, promptly at midnight, and Ashton will be electrocuted.
An automated gangster dummy opens fire and MacGyver and Murdoc duck for cover. MacGyver throws a cabbage from a garbage can to draw its fire and then knocks it out with an apple. Two more open fire and MacGyver throws a garbage can lid to draw their fire so he and Murdoc can escape into the jungle setting. Ashton calls out, warning them about the concealed machine gun that killed Greggs. It opens fire and MacGyver realizes that it uses motion sensors to track them. He has Murdoc draw its fire while he comes around at it from the side and drapes a cloth over the motion sensor.
MacGyver and Murdoc go to the passageway leading to Ashton. Helman cuts off their retreat with a gate and then opens the floor. The pit below is filled with snakes. Murdoc admits the one thing he's afraid of is snakes. MacGyver uses the kerosene from a torch to douse the snakes, repelling them. He has no choice but to carry Murdoc on his back as he walks through the pit. On the other side, they quickly free Ashton and pull her away just as the chair electrifies. Helman closes the floor and comes after them, shooting Murdoc in the shoulder. As he prepares to administer the final shot, Murdoc tells MacGyver to go and take Ashton with him. Helman enters the passageway but Sonya double-crosses him, opening the pit and dropping him in with the snakes. Murdoc tosses his grenade in, finishing off his mentor for good.
MacGyver escorts Ashton to the airport where she'll return to her normal life. She assumes Murdoc was MacGyver's friend and expresses her condolences at his loss. Once she's gone, MacGyver discovers an envelope in his truck. It's Murdoc's promised evidence against H.I.T. There's also a tape recorder, and Murdoc admits he has no intention of turning himself in. He laughs and warns MacGyver to keep looking over his shoulder.