4 books in series

The Mysterious Benedict Society

The Mysterious Benedict Society is a 5-book series with 4 released primary works first released in 2007 with contributions by Trenton Lee Stewart.

The Extraordinary Education of Nicholas Benedict
The Mysterious Benedict Society
The Mysterious Benedict Society and the Perilous Journey
The Mysterious Benedict Society and The Prisoner's Dilemma
The Mysterious Benedict Society and the Riddle of Ages