From the back of the book:
Henry, Jessie, Violet, and Benny used to live alone in a boxcar, but now they live with their grandfather. And they've just made a new friend named Beth.
The Boxcar Children decide to raise money to help the Greenfield hospital. At Beth's suggestion, they form a service called The Boxcar Helpers - to baby-sit, wash cars, mow lawns, and care for pets. But Beth keeps disappearing. And then other things start to go wrong. Is someone trying to put them out of business?
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ISBN-13: 978-0-8075-1628-7
ISBN-10: 0-8075-1628-7