Season synopsis
Contains spoilers for this season and earlier seasons.
A year after Dick Roman's death, Dean escapes Purgatory with the vampire Benny, while Castiel remains behind. Sam has stopped hunting and never searched for Dean, so their reunion is strained. They return to the work when Kevin Tran escapes Crowley with a demon tablet explaining how to close Hell's gates. As Kevin translates it, Dean tries to help Benny adjust to life on Earth and the brothers' separate responses to their year apart complicate the hunt.
The tablet sets three trials: kill a hellhound and bathe in its blood, rescue an innocent soul from Hell, then cure a demon. Sam insists on doing them even as the work damages his body. For the second trial, he travels alone through Purgatory to reach Hell and rescue Bobby's soul. When the reaper Ajay is killed before Sam can return, Dean asks Benny to go back and lead Sam out. Benny stays in Purgatory so Sam can escape with Bobby's soul, and Sam completes the trial by delivering Bobby to Heaven.
The brothers capture Crowley for the final trial, which requires Sam to cure him. Naomi warns Dean that completing the trials will kill Sam, and Dean stops him before he can finish the ritual. Sam collapses from the damage already done. Castiel has separately followed Metatron's angel trials, believing they will close Heaven's gates; Metatron takes Castiel's grace and completes a spell that expels the angels instead. The season ends with Sam and Dean beside the Impala as angels fall from Heaven.