Meet the Sinister-Winterbottoms: brave Theo, her timid twin, Alexander, and their older sister, Wil. They're stuck for the summer with their Aunt Saffronia, who doesn't know how often children need to eat and can't use a smartphone, and whose feet never quite seem to touch the floor when she glides-er-walks. When Aunt Saffronia suggests a week pass to the Fathoms of Fun Waterpark, they hastily agree. But the park is even stranger than Aunt Saffronia....

The third book in the middle-grade series that's part Scooby-Doo, part A Series of Unfortunate Events, and entirely genius! Follow the Sinister-Winterbottoms on their most outrageous adventure yet, when they find themselves at a normal summer camp! After leaving the Sanguine Spa in pursuit of Edgaren't, the kids find themselves at a mysterious summer camp, Camp Creek. There are lake games and happy counselors, and there's even a tie-dye cabin. It's...

Following the clues left behind, Theo and Alexander find themselves at Siren's Song Seaside Amusement Park, where they must work together to escape, stop their newfound nemesis Essa, save Wil and their friends, and find their parents.