'The Bowman triplets always attract trouble. So when twelve-year-olds Michael, Luke and Samantha ruin a classmate's costume party, they're chased by the school bullies into the city sewers. Locked inside, they discover a different kind of exit . . . A Knock-Knock Door.
'It's a gateway to another world, where sharks fly, swashbucklers scheme and party costumes become real. Soon, the triplets are mistaken for famous heroes and enlisted to fight the biggest trouble of all: a rampaging monster.
'Can you solve the puzzles and help bring our three adventurers home?' (From the publisher's website.)