Just off a long stakeout, Don's weary team puts in another sleepless day-and-a-half when they become part of a rescue/investigation after a freight train transporting toxic chemicals crashes into a passenger train, obliterating the black boxes. As Charlie's bots map the site, Amita tries to determine the collision's cause, Nikki sees only one possible scenario, and David chomps at the bit as more victims are jeopardized.
—layle