A middle-grade mystery series that's spooky, creepy, and filled with gothic twists! Meet the Sinister-Winterbottom twins, who solve mysteries at increasingly bizarre summer vacation destinations in the hopes of being reunited with their parents--or at the very least finally finding a good churro. "An absolute delight. If I have to die in a waterpark, I want to die in this one."--Holly Black, #1 New York Times bestselling author...