The Graham Quartet and the Mystery of the Day Maid

Arriving on the shore of Lake Michigan for summer vacation, the Graham Quartet senses that something is not quite right. When a slip of the tongue causes an unexpected reaction, Elsa, Matt, Selena and Tim jump into a mystery. But what is the connection between a cryptic note, a yellow door, and a boat called the Day Maid? When their friend, Lieutenant Ashwood, disappears, the Quartet feels the pressure of time and must turn to another source for help. Will the four siblings get enough information to unravel the mystery before the suspects vanish completely?