Ghosts

While unusual circumstances are practically usual, a body drowned in a bathtub of motor oil has the team scratching its collective head. The mystery deepens when investigation shows that the victim may have been involved with a crime more than 20 years old and was working with, or being stalked by, a true crime writer, and the relationship between Castle and Beckett finally rears its truly competitive head during a poker game involving New York's legal system elite.