When valuable cargo ships vanish from Rockfall Mountain's busiest port, crime-fighting goblin detective Fizz Marlow and his troll sleuthing partner, Tank Wrenchlin, know Dectective Hordish is going to need their help (whether he wants it or not). But it's Tank's mom, the harbor master who is really feeling the heat. It's her responsibility to keep the harbor safe, and the lost ships quickly cost her her job. Determined to help, Tank, Fizz and their wizard pal, Aleetha, dive into this new mystery, only to get tangled up with a terror from below that takes the detectives far from home and puts them snout-to-snout with a band of vicious kobold pirates. The Case of the Tentacle Terror is the fifth book in the Tank & Fizz series about two crime-solving monsters living under a mountain.