Supernatural, season 10

Demon Dean lasts a summer - karaoke, Crowley's road-trip companion, cheerfully awful - until Sam drags him home and cures him with consecrated blood, the season's first mercy. But the cure removes the demon, not the Mark: it is still on his arm, still hungry, and the year is the study of a man white-knuckling his own arm.

The search for removal runs through the season's furniture: Charlie and the Book of the Damned, a family of book-hoarders called the Styne, Rowena - Crowley's mother, witch, delight and menace - and Cain himself, farming bees and bodies, who tells Dean exactly how the arc ends: first Crowley, then Castiel, then Sam. Dean kills him with his own blade and hears it as prophecy.

Charlie dies for the book - the Stynes' doing, and Dean's rampage in answer is the Mark with the leash off. Sam, forbidden to pursue the cure, pursues it anyway with Rowena's codebreaking, and the finale prices the choice: the spell works, the Mark lifts - and Death himself, consulted, had warned it was not a curse but a lock.

The last minutes are reversal on reversal: Dean, asked by Death to remove Sam, swings the scythe into Death instead; Rowena completes the spell and slips her chains; and the Darkness - the thing God locked away before light, held shut by the Mark since Lucifer wore it - rolls out of the ground as a black tide and takes the Impala inside it.