Elizabeth Enright

Four New York City siblings decide to pool their resources so that each can do a special thing on the Saturday that is his turn to receive the combined allowance.

A summer that promises to be eventful turns into something extra special when the four Melendy children become friends with the orphaned Mark Heron.

Unusal things begin to happen when a young girl finds a silver thimble.

Mona, the eldest, is thirteen. She has decided to become an actress and can recite poetry at the drop of a hat. Rush is twelve and a bit mischievous. Miranda is ten and a half. She loves dancing and painting pictures. Oliver is the youngest. At six, he is a calm and thoughtful person. They all live with their writer father and Cuffy, their beloved housekeeper.

Mona, Rush, Randy, and Oliver Melendy consolidate their allowances, form the Independent Saturday Afternoon Adventure Club, and take turns spending the money to attend concerts, plays and art exhibitions.