On this episode of Supernatural…

Mary continues to work with the British Men of Letters, even turning down working with Sam and Dean on a hunt.

Crowley reveals he found Lucifer’s vessel and messed with Rowena’s spell when she and the Winchesters tried to send Lucifer back to the cage. It sent him to the vessel where Crowley could watch over him.

Sam and Dean take on a ghostly case involving a ship that Crowley’s son, Gavin Macleod, was supposed to be on when it sank.

Kelly Kline is attacked by angels but Dagon, a prince of hell, saves her.

Gavin’s girlfriend got on the ship, and is the ghost attacking people.

Gavin chooses to go back in time to get on the ship, protect his girlfriend, thus stopping her from becoming a vengeful spirit, and die on the ship he was supposed to.

Mary reveals to Sam and Dean she’s been working with the British Men of Letters.

Rowena reveals why she stopped Crowley from stopping Gavin, partly because it was the right thing to do, but mostly as payback for Crowley making her kill her son.