Take the format and time period of “The Canterbury Tales”; update the language; create a fantastical story about “three magical children and their holy dog”; and you have “The Inquisitor’s Tale,” a 2017 Newbery Honor book and one of the most fascinating and unusual middle-grade novels to come along in years.

Adam Gidwitz’s story concerns three children who live on the outskirts of their medieval French society: Jeanne, a peasant girl; William, a half-African oblate (monk in training); and Jacob, a young Jewish boy. Despite their humble and obscure backgrounds, the children have become something of a legend in their time — wanted by the king of France himself.

The story opens with a group of travelers at an inn trading stories about the children’s journeys together, and their mysterious powers and radical mission that have most people considering them either saints or heretics. One guest in particular — the narrator of our story — has a secret reason for wanting to know more about the children: a reason that could lead to their rescue, or their downfall.

This colorful tale is told with great charm and wit, aided by Hatem Aly’s imaginative illustrations. It’s full of twists, turns, and surprises, some of them dangerous ones. At first, the children are afraid of each other, and not without reason. William has been taught that girls and Jews are inherently evil; Jacob has seen his village burned to the ground by Christian boys; and Jeanne, having been arrested for claiming that her dog, Gwenforte, was a resurrected saint, is afraid to trust anyone. But having been forcibly thrown together when they were taken by knights, the three must rely on one another, and soon manage to befriend each other despite their great differences.

But the children are often treated roughly by the adults around them, and they have a hard time figuring out whom to trust aside from each other, and who might be a threat to their very lives. Along the way, however, they learn to accept, to forgive, and to show great courage and loyalty.

As implied above, faith is a very real force in the lives of the children and everyone around them, with miracles, angels, holy books, and theological debates often taking center stage. (Given the time period, it makes sense that the faith practiced by nearly all the characters is Catholicism, so a belief in saints and relics is part of their lives.) Sometimes faith is used as a cover for superstition, intolerance, and worse, as when Jeanne is arrested, when Jacob’s village is burned and his parents killed, and when the queen mother is determined to burn every Talmud in France. But the children and their sometime guide — a red-haired monk named Michelangelo who turns out to be much more than they expected — hold fast to their belief in a God who loves and values everyone, and this belief increasingly guides their thoughts and actions.

At times, however, the story flirts with the idea that religious differences don’t matter at all. This is a tricky area, one where parents will want to help their kids draw some important distinctions. For example, the children’s growing understanding that all people should be treated equally is commendable, as is Jeanne’s and William’s eventual realization that a Jewish book might contain wisdom and not deserve to be burned. More worrisome is the idea that it might not matter so much whether someone believes in Jesus or not, or the idea that one might not need to be a Christian to become a Christian saint. These and similar ideas are often only hinted at, not actually spelled out, but they’re still something to be aware of.

The story brings the medieval world to vivid life, with all the earthiness and lack of hygiene that implies. There is some bathroom humor — most notably in the episode of a farting and vomiting dragon — and occasional mild profanity. There’s also violence, though much of it is similar to the fantasy kind. (William first demonstrates his powers, for instance, by tearing the leg off a donkey — which doesn’t even seem to notice — beating a bunch of fiends to death with it, and then instantly reattaching it to the donkey.)

Despite some questionable ideas and a couple of gross-out moments, “The Inquisitor’s Tale” is, on the whole, a delightful story. If the theology isn’t always on target, the concept of respect and love across religious boundaries is nonetheless conveyed in touching and enlightening ways.

Image copyright Dutton Books for Young Readers. Review copy obtained from the publisher.

Gina Dalfonzo is editor of BreakPoint.org and Dickensblog, and the author of “One by One: Welcoming the Singles in Your Church” (Baker, June 2017).