This sequel to the New York Times bestselling book The Mystery of Locked Rooms follows the beloved Deltas as they race to complete the most challenging escape room they've ever faced...and confront their fears in order to save their friendship.When a strange invitation shows up in Sarah's backpack, the Delta's learn that their favorite funhouse, The Delta Game, is about to get some serious competition. The "Mystery Mansion" is opening just miles away and the ominous and cryptic owner has invited Sarah, West, and Hannah to come test it on opening day. It claims to be the biggest and best escape house ever, and based on the photos of gleaming rooms filled with high-tech puzzles, it just might be.What's more, the kids have been offered a ten-thousand-dollar prize if they escape the house. For some reason, West and Hannah seem very interested in the cash prize, but the three friends are torn because they really don't want to be a walking advertisement for a competitor to The Delta Game. After all, that funhouse changed their lives, Sarah's life especially.But maybe the only way to keep the funhouse, and their friend William Taters in business, is to accept the invite to this new Mystery Mansion, escape it in record time, and show just how lame and easy it is by comparison. The trio arrive at the mansion on opening day, armed with their "fortune favors the bold" attitude. But they quickly learn that nothing is as it seems . . . and unfortunately this time, not everyone plays fair.