Marty and Grace O'Hara's globe-trotting parents disappeared while on assignment for a nature magazine, and now they're living with their Uncle Wolfe, a scientist fascinated by cryptids - creatures that appear in myths but haven't been proven to exist, such as the Loch Ness Monster.

Wolfe is planning an expedition to New Zealand to track a giant squid, and he's rented a huge (and possibly haunted) freighter for the trip. But someone on board is determined to sabotage their mission--and if Marty and Grace keeping poking their noses into things, they might end up the saboteur's next victims!