Tonight's all new-episode, "The Limey," brings us an uber-hot Scotland Yard police detective on a stateside search for the man who murdered his friend's daughter. The prime suspect? Nigel Winthrop, Deputy General at the British Consulate.
Will Castle and Beckett be able to put their relationship issues aside and solve the case?
Tune in to Season 4, Episode 20: "The Limey" tonight at 10 p.m. ET on ABC. If you can't wait that long, check out our sneak peeks and spoilers roundup for a little taste of what to expect.