Rick and Kenny's Pa was right—troubles really do happen in threes. First Pa's truck was robbed, then Pa ran off, leaving Rick, Kenny, and Ma to fend for themselves, and now Ma has disappeared, too. Rick just knows Ma would never leave them on purpose—but then, where is she? Waiting in Uncle Henry's trailer park doesn't seem like the best way to find out. Instead, the brothers, along with their new friends, Connie and Julie, decide to search the abandoned Wonderland Amusement Park next door for answers. But what they find inside sends them on the most terrifying roller coaster ride of their lives—could whoever took Ma be after them, too?