"Tick, Tick, Tick..." is the 27th episode of Castle and the first of a two-part story, concluding with the following episode, "Boom!". It is the 17th episode of the second season. The episode was written by Moira Kirland and directed by Bryan Spicer. It first aired on March 22, 2010 on ABC. In the episode, Rick Castle (Nathan Fillion) and Kate Beckett (Stana Katic) must team up with the FBI to track down a killer (Dameon Clarke) using one of Castle's books as inspiration.