Schoolhouse 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 are spending the summer in a remote fishing village on the New England coast.

Benny is suspicious of a man he sees snooping in the village library. Who is he? And why does he hide from Benny? The Boxcar Children don't know the man's secret yet. But they are about to find out!