Billie Bradley and Her Classmates

Billie and her chums come to the rescue of several little children who have broken through the ice. There is the mystery of a lost invention, and also the dreaded mystery of the locked school tower. (Summary from original advertisement) This is the fourth book in the "Billie Bradley" series, a mystery series for girls. Janet D. Wheeler is a pen name used by the Stratemeyer Syndicate for the Billie Bradley series.