The Circle of Footprints — Carolyn Keene

The Dana girls are plunged into another mystery when they befriend the Doke family shortly after Mason Doke unfortunately crashes into their uncle's ship with his airplane. The Danas interrupt a burglary at the Doke home and discover that the would-be thief was attempting to steal a box full of money.

Mrs. Doke fears greatly that the money was stolen by her husband, and the Danas assume responsibility for the money until Mrs. Doke can decide what to do with the money. The thief learns from Lettie Briggs that the girls live at the Starhurst school, and the girls are forced to move the money several times in order to prevent a theft.

Mr. Doke dies of his injuries, and Mrs. Doke requests that the girls help her discover the rightful owners of the money so that she can right the wrongs of her husband. The Danas face many harrowing adventures as they search for the owners and narrowly escape being poisoned by an insane woman.