During the high-profile trial of a murdered socialite, a juror suddenly tumbles out of the jury box -- dead! When Castle & Beckett learn the juror was poisoned, their investigation soon uncovers that this seemingly innocent juror may not have been so innocent after all.

When a champion swimmer and Olympic hopeful is found dead in a training pool, Castle & Beckett dive in to investigate his murder, and uncover myriad secrets that might have led to his death. Also in the episode, crime fiction authors Michael Connelly and Dennis Lehane guest star, offering Castle their insights into the case over a game of poker.