There’s chaos in Heaven.
After weapons like the Staff of Moses are stolen from Heaven, Sam and Dean call on Castiel for help. That’s when they learn of the angel civil war and Castiel’s desperate attempt to fix everything.
However, the archangel Raphael seeks to find the weapons, take over Heaven, and set the apocalypse back on track. Luckily, Castiel has a little help from a fellow angel to slow Raphael’s goals down.