Gustav Is Missing!

Little Cap is a young mushroom who is devoted to Gustav, his pet slug. When Gustav vanishes, Little Cap is thrown into a panic and wonders whether he can possibly leave the snug house he has always known to search for his friend.

When he does step outside, the world beyond his door turns out to be full of unsettling figures, and he must also approach the neighbors for help. Through every obstacle, Little Cap keeps pushing forward in his search.