Duff's dad thinks his son has an over-active imagination: one day their neighborhood is menaced by flying saucers, the next by stray elephants or boa constrictors.

So when Duff announces he's found a monkey in the barn, no one believes him. No one, that is except his best friend Simon. The harder Duff and Simon try to convince people that the monkey is real, the less they're convinced. Simon's mom takes her worries to the rabbi; Duff's priest preaches sermons about the dangers of lying.

When Mr. Antonio comes to town looking for the star performer of his Mountie Monkey Act, however, people think twice about what Duff and Simon said, and about how they responded to it.

Duff's Monkey Business is a hilarious story about the importance of honesty, and of keeping an open mind to the truth.