Flowers in the Attic by V.C. Andrews is a tale of four children, one a ballet dancer, who get locked away in a bedroom in a behemoth mansion with only an attic to play in, while their mother waits for her father to die so she can inherit millions.
Great hook. And as a kid, I loved this book. As an adult, rereading it, well, the writing isn't so fabulous.
What childhood favorite book have you reread as an adult that left you less than dazzled?