The Lighthouse 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 lighthouse on the New England coast.

Jessie sees a mysterious woman walking on the grounds of the lighthouse late at night. Watch, Jessie's dog, wakes up growling almost every evening -- at midnight. And Henry finds a puzzling note in the sand....

Many more strange things will happen before the Boxcar Children can solve The Lighthouse Mystery.