Not long after her family becomes wealthy, Diana Lynch's long-lost uncle appears and starts ruining her social life, causing Trixie Belden to investigate whether Uncle Monty is an imposter out to steal the Lynch fortune.
While spending Christmas break at an Arizona dude ranch, Trixie and the Bob-Whites work to solve several mysteries--a phony cowboy, disappearing staff, and puzzling cries in the night.
While organizing an ice carnival to raise funds for her pen pal's school library, Trixie investigates a mysterious problem facing Regan and a run of thefts and accidents in the neighborhood.