The Chocolate Sundae Mystery — Gertrude Chandler Warner

One warm night four children stood in front of a bakery. No one knew them. No one knew where they had come from.

Henry, Jessie, Violet, and Benny used to live alone in a boxcar. Now they have a home with their grandfather, and they're helping out at their favorite ice cream store in town, the Shoppe.

When very strange things begin to happen, the Shoppe is in danger of losing its customers and of going out of business. Can the Boxcar Children solve the mystery and save the Shoppe before it's too late?