After returning home from an afternoon at Lydia’s, Y/n McCall discovers that her brother, Scott, has bitten a classmate, Liam Dunbar, to save his life—and is now keeping him "hostage" in their bathtub. An instant, bitter rivalry sparks between Scott’s cynical, brilliant sister and the new, hot-headed Beta: she sees him as an ungrateful, dangerous brat, while he views her as nothing more than the pack’s arrogant human "babysitter."