|Original Airdate||February 8, 2001|
Boom is the thirteenth episode in season one of CSI: Crime Scene Investigation
Grissom, Sara and Warrick investigate when a bomb goes off in a Vegas office building, killing a security guard. The prime suspect is another security guard, who is over-helpful and also has the knowledge to make a bomb. After Nick spends the night with Kristy Hopkins, she is killed. With his DNA and fingerprints on the scene and Ecklie on the case, Nick's career is on the line.
A pipe bomb explodes in the lobby of the Hansen office building. The CSIs arrive at the scene and collect the scattered bomb fragments; they find a cog with “FP” scratched into it and another with an orange substance melted on it.
Dominic, a security guard for the building, approaches Grissom and offers to help the investigation, touting his extensive knowledge about bombs. Grissom immediately becomes suspicious and takes Dominic up on his offer in order to keep a close eye on him. When Warrick and Brass interrogate him, he quickly asserts that he gained all of his knowledge of bombs through trial and error, completely oblivious to the fact that he is under suspicion.
Grissom and Sara discover that a SnoozeWell clock was used in the bomb’s timing mechanism, and Brass delivers the news that Dominic has bought many SnoozeWell clocks recently. They visit Dominic, who eagerly shows them his wide assortment of bomb parts and tells them about his hobby of building bombs and exploding them in the desert. Dominic is shocked when Brass arrests him for the Hansen bombing.
Another bomb explodes at the Thrift-Right car rental agency and the CSIs arrive to process the scene. Grissom finds a mousetrap covered in the same orange substance, and he realizes that the bomb timer is triggered by motion, when someone picks up the bomb. Sara notices a rental-car agent wearing an orange jacket and collects it.
Dominic is released from jail and Grissom warns him to not be so trusting.
Tests show that the orange substance is a match to the jacket. Sara also learns that Thrift-Right’s corporate headquarters are in the Hansen building, and that a Norman Stirling was recently let go. He has been unemployed since.
Warrick discovers that the tool used to etch “FP” into the cog was an etcher sold to the high school attended by Stirling’s son, Tyler. Grissom and Brass question him, and he confesses that “FP” stands for “fair play”, a phrase Norman constantly shouted when he was fired. Norman is horrified to learn that his son is responsible for the bombs and demands to know if Tyler made any more; Tyler tells them about a bomb at his high school.
Dominic learns of the bomb through his police scanner but rushes out of the room before hearing that the bomb is trigger-activated. He finds the bomb at the school and carries it out of the building, but the bomb explodes in his hands.
Nick goes to a casino where he sees Kristy Hopkins arguing with a man, Jack Willman. Nick breaks up the fight and drives Kristy home; she invites him inside and they have sex. The next morning, Nick returns to Kristy’s and is shocked to find crime scene tape surrounding the house. Ecklie, who is processing the scene, tells Nick that Kristy was strangled to death.
Nick, panicked, tells Grissom everything and says that Ecklie will find his fingerprints and DNA all over Kristy’s house. He offers to explain everything to Ecklie but Grissom orders him to keep his mouth shut, saying that he will talk to Ecklie instead. Grissom notes that even if Nick is cleared of the charges, simply being arrested is enough to earn him an automatic dismissal from the lab.
Nick tells Ecklie about Jack, and Ecklie interrogates Jack, who says that he saw Nick strangle Kristy in her room through the window. Ecklie moves to arrest Nick, but Catherine asks for twelve more hours to clear him.
Catherine returns to Kristy’s house and finds the murder weapon: the tie-back cords on the curtains. Greg runs tests and finds that the DNA of the epithelial cells on the cord matches Jack Willman. Nick was framed. Jack is arrested and Nick confronts him; Jack says that he killed Kristy because he was her pimp and she was going to leave him.
- Tyler's etching of "FP" on the bombs is similar to that of Theodore Kaczynski, otherwise known as the infamous Unabomber's etching of "FC" on his bombs. However, unlike Tyler's etching, which stood for "Fair Play", Kaczynski asserts his etching stood for "Freedom Club".
- Tyler's etching of "FP" on the bombs is a reference to George Metesky, the so-called "Mad Bomber" who terrorized New York City in the 1940s and 50s. Metesky had been fired by Con Edison and, like Tyler's father, was unsuccessful in reclaiming his job. He signed all the notes placed with his bombs "FP", standing for "Fair Play".