Junkie Jordy Thompkins was shot dead in an alleyway, but the bullet that killed him is missing. Taylor and Hawkes soon realise that a rat may have eaten the bullet, and finding the rat leads them to a robbery that occurred earlier that day. After Robin Prescott is found raped and beaten in Central Park with only a peony leaf on her clothing, Stella and Flack have the daunting task of trying to find the man who raped her, but Prescott has no memory of the crime.

After a routine call leads two of the team into finding a bomb, they evacuate but a few are still in the building along with Mac and Flack when the bomb detonates. After the explosion the CSI's face a race against time to find the bomber and the possibility of losing one of their own. Mac must come to grips with having let a Marine die in Beirut in 1983.