The Wishbones are a happy family - but not all is perfect. Max and Fay are struggling with the pressures of growing up, while Mom and Dad have the demands of work and parenting; but their hum-drum life is about to change. Mila Starr, a monster hunter, has made it her mission to capture all spooky creatures including the Wishbone's friends King Conga, The Loch Ness Monster, and The Yeti. In order to save their friends, the Wishbone's must transform into monsters themselves. Together as a Vampire, Mummy, Werewolf, and Frankenstein, the family take off on the most monst-umental adventure of their lives.