5. Probable Cause

While investigating a shocking ritualistic murder, Beckett and her team uncover surprising evidence linking Castle to the killing. As the evidence against him mounts, loyalties are tested, and when surprising revelations come to light, Beckett begins to wonder how well she really knows her new lover and partner of four years.

Plot summary and ending

Spoilers ahead. Coverage follows the scope labeled below.

Complete story — includes the ending

When investigating a brutal ritual killing, Beckett is horrified when the evidence leads her straight to Castle and she is forced to confront the idea that Castle may be capable of murder. As the evidence against him piles up, Castle orchestrates his own prison break when he learns he has been set up by Jerry Tyson, better known as the Triple Killer (3XK). As he becomes the target of a city-wide manhunt, Castle must stay alive long enough for Beckett to catch Tyson before Tyson catches him.

Sources and content license

Source and revision history · Adapted from Wikipedia contributors, Castle season 5. HTML formatting and reference markers removed. · Content license