Supernatual meets the Peculiar Children

Peculiar Children run into the Leviathan who have now found a way to posses the hollows, making them more powerful and dangerous, as they are now hungrier for living flesh. Upon hearing of a towns peculiar problem of missing persons and animals found dead, the Winchester's take it upon themselves to investigate and join the peculiars in taking down the new abomination.

This story takes place after season 7(but also after Dean returns from Purgatory) in Supernatural and in the middle of book 2 of Miss Peregrine's Peculiar Children.