The sixth season of this crime drama opens with Beckett (Stana Katic) accepting a marriage proposal from Castle (Nathan Fillion). However, their road to the altar gets a little bumpy when Beckett also accepts a new high-profile job in Washington, D.C. Meanwhile, things don't go smoothly for Castle and Alexis (Molly Quinn) when he doesn't approve of the new boyfriend she's brought home from Costa Rica. Castle gets a glimpse at what parenthood would be like a second time when he and Beckett temporarily care for a baby who was carried into a church by a man dying from gunshot wounds. And Ryan (Seamus Dever) and his wife excitedly prepare for their first child, but she goes into labor while Ryan is investigating a dangerous arson case.

This release compiles all 23 episodes from the fourth season of Castle. This run of shows finds Beckett getting closer to the truth about her mother's death, as Castle grows more protective of her.