Percy Wynn is a "girlish" boy raised with 10 sisters, but Tom Playfair, his new friend at a Jesuit boarding school, decides "to make a boy" of him.

In this volume, Tom Playfair meets a new boy just arriving at St. Maure's. Percy Wynn has grown up in a family of 10 girls and only 1 boy--himself! His manners are formal, he talks like a book, and he has never played baseball or gone skating, boating, fishing, or even swimming! Yet he has brains, courage and high Catholic ideals. Tom and his buddies at St. Maure's befriend Percy and have a great time as they all work at turning Percy into an all-American Catholic boy.