Timothy B. Quibble is an unusual child. His closest friends are insects, which makes the first chapter -- in which we see his luna moth Moonbeam devoured by a bat mere moments after emerging from a chrysalis -- all the more tragic. He keeps a praying mantis named Maximilian in his pocket as a pet. He has one good friend in middle school, but otherwise he is the target of constant teasing, even bullying.

He tries using humor to deflect his tormenters, but it rarely works.

His mother is distant and disinterested, concerned more with wealth and image than the wellbeing of her son. She doesn't know or understand him, and she doesn't care enough to try. His father is dead, although his death -- when Tim was 3 years old -- still looms large over his life. His paternal grandparents remain close, but his mother resents their influence on his life.

Now 11, Tim is too timid to stand up for himself, hoping for little more from each day than to make it through without humiliation and, if he's lucky, to find an interesting bug specimen to add to his little zoo.

Then he finds out his mother is marrying a man he didn't even know she was dating. Heck, he didn't know she was dating anyone. Before he has time to get used to the idea, she tells him this new guy and his daughter are moving in with them. Immediately. And soon, she adds, they are selling their home and moving to a larger place ... far from his grandparents and his one true friend.

Then one day, his reflection in the mirror goes a bit ... off. Soon, his shadow develops independence, too, growing and contorting into something monstrous -- a misshapen shadow that initially just follows him around, but as it grows it seems to promise to help him take control of his life.

It's a promise he can't resist.

Tony DiTerlizzi's The Wump has a strong premise, but somewhere near the end the story goes off the rails. Tim's reliance on the Wump, as he dubs his shadow monster, evolves from simply standing up for himself into actual malice. The tormented becomes the tormentor, and he even starts hurting the people he cares about. The denouement is a frenzy of destruction and vandalism that goes well beyond simple mischief ... and in a real world, the consequences would be far more severe than anything Tim faces here.

Without giving away too many details, Tim eventually takes on a degree of independence and self-determination that might make sense in a young adult -- or even an older teen -- but which would never work for an 11-year-old boy. The forgiveness he earns and the bridges he mends by the end far exceeds anything an actual human child could expect, and the "where are they now" conclusion to the book feels like a desperate attempt to tack on a happy ending that wasn't earned.

DiTerlizzi has impressed me in the past with his work as an artist, particularly his partnership with author Holly Black on The Spiderwick Chronicles, but this is my first encounter with DiTerlizzi as an author in his own right. Sadly, while I enjoyed the book almost to the end -- in particular enjoying his character building and quirky, whimsical writing style -- he should have rethought his finale before going to print. The Wump goes dark by the end, and then it tries too hard to bring back a little light that, unfortunately, no longer suits the story.