The Mystery of the Gulls — Phyllis A. Whitney

Taffy Saunders finds mystery and adventure on beautiful Mackinac Island, where her mother has unexpectedly inherited a hotel. A stipulation in the will states that Mrs. Saunders must manage the hotel successfully for a summer in order to gain title to it.

Taffy and her mother arrive at Sunset House to find the little hotel enveloped in an atmosphere of mystery and antagonism. Celeste, the exotic and superstitious French-Indian cook, has gone on strike and the housekeeper and her daughter seem strange and unfriendly. But it is not until mysterious happenings scare the guests into leaving that Taffy realizes someone wants her mother to fail. Who? Why? There are questions she must answer.