Winterborne Home for mayhem and mystery - Ally Carter

FIVE EXTRAORDINARY ORPHANS. ONE INCREDIBLE MYSTERY.
UNLOCK THE SECRETS OF THE WINTERBORNE HOME FOR VENGEANCE AND VALOUR.

April is one of five foster kids living at Winterborne Home, a sprawling mansion full of secrets. The biggest secret is that Gabriel Winterborne, their reclusive millionaire guardian, is actually The Sentinel, a masked vigilante tasked with protecting the city.
When Gabriel goes missing (again!) it's up to the kids to find him before his enemies do. And when April's past catches up with her, she will have to decide how hard she's willing to fight to hold on to her new-found family when everyone seems determined to tear them apart ...

Join April and her ragtag group of friends as they unravel family secrets, creepy legends and mysterious identities in the second book in the captivating new middle-grade series from the bestselling author of Gallagher Girls.