They find a lot more than either anticipated, and it’s pretty easy to guess what at least one of those things is: their father.
Sam and Dean will turn to occult lore during their search for the solution to a problem, which may be the case of the week or may be Dean’s potential fate as trapped in a box at the bottom of the Pacific with Michael in his head for all eternity.
The abundance of weirdness may come from scenes not teased in the trailer.