"First Edition: October 2009" stated on copyright page; Little, Brown and Company publishers; hardbound; very good condition of book and dust jacket.
 
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The Mysterious Benedict Society and the Prisoner's Dilemma is a 2009 children's novel written by Trenton Lee Stewart and illustrated by Diana Sudyka. For a decade it remained the third and final book in the Mysterious Benedict Society series; however, a new adventure followed in 2019.
 
In the third installment of the Mysterious Benedict Society series, Reynie, Sticky, Kate, Constance, and various loved ones find themselves holed up in Mr. Benedict's house, which is teeming with security. The evil Mr. Curtain is at large and hunting for the Whisperer—now in Mr. Benedict's possession—so he can control minds from afar. When a shady businessman shows up with false records claiming that he is Constance's father, Mr. Benedict is compelled to use the Whisperer to uncover her short past. Distraught and confused after all is revealed that she is an orphan, Constance runs away, with the whole household after her—just the distraction Mr. Curtain and his men need to steal the Whisperer and set his evil plans into motion. Of course, the rest of the Mysterious Benedict Society soon find themselves on his trail...