Twin brothers discover their new home is also a portal to a parallel dimension in this spine-chilling middle-grade adventure, perfect for fans of The Mysterious Benedict Society--now available in paperback! Colm and Mal are twins so identical their own mom can't tell them apart, but they're different in just about every other way. Mal's a pragmatist while Colm's a dreamer, and they bicker and battle constantly. Neither brother is excited to be moving to Chicago for a fresh start with their mom just after their dad's death. But nothing cures homesickness like intrigue--and their new home, Brunhild Tower, has plenty of it: mysterious elderly neighbors who warn against wandering the building at midday, strange sounds in the walls, and an elevator missing a button for the thirteenth floor. One day, that button appears. And when the doors open on the missing floor, the boys are greeted by the strangest--and spookiest--puzzle yet: a twin building that is stuck in time and bustling with activity. All of Brunhild Tower's former residents live on in this phantom tower, where the rules of the real world don't apply. But when the brothers and their newfound friends discover they're all trapped by an ancient curse, they must band together to set everyone free before it's too late.