Bart Flynn, a developer looking to build a casino, is holding a masquerade game night for potential investors. There are environmental protesters outside the event. Then comes an explosion. Maxine summons a team to the scene of the fundraiser, which has been cleared by the bomb squad. There are three victims and a spare foot. A second explosion goes off, sending Josh flying. Trey is attempting to reach Folsom about his mother. Josh skips getting checked outl to find Trey. A second sweep shows there were actually four blasts. Trey lied about Folsom's mother. Instead, he has a dead man, Richie, in his apartment. Greg, Penny, and Chris join the search. Greg and Catherine reunite. Penny finds the detonator. Beau's theory is that there weren't multiple bombs. Max suggests that the bombing was targeted. The killer was in the tent and set off the bomb manually. Trey lets slip that Josh and Allie were once close, which surprises Serena. She chastises Folsom for not going to the hospital. The man who lost the foot was Clnt's site coordinator, Van, who claimed to remember nothing. Bart was the intended victim. Bart's daughter Haley is caught in a lie. Folsom tells Serena that he thinks Richie was in Trey's apartment looking to score. Beau thinks that a metal toke box was used for the bomb. Josh finds drugs hidden in Trey's apartment. Chandara, the pit boss, says that Haley was at the party but threw her mask when she left. Haley has a history as an eco-extremist. But she claims all she did was let in environmentalist Rhonda. Max convinces Folsom to turn in Trey. Greg has decided he wants to come back to work full time and eventually teach forensics. Cicero built and set off the bomb. Serena arrests Trey.