Tower of Treasure by Scott Chantler

The first book in the Three Thieves series, Dessa's mother was killed and a stranger took her twin brother away when she was just a small child.  Now 14, Dessa is an acrobat in a traveling circus, still hoping one day to find her brother.  In the city of Kingsbridge, after a bungled treasure heist from the Queens own treasury with her friends Topper, a goblin like creature and Fisk a one-headed Ettin (they usually have two), Dessa comes face-to-face with the man who took her brother.  Unfortunately for her, the man is the Queen's chamberlain.  Dessa will do whatever it takes to learn the truth and find her brother.

This was lots of fun.  Dessa is strong, spunky and smart.  She's fiercely determined to find out what happened to her brother, even though she knows she's going up against tough odds.  She's got her two friends to help her, although they often cause more trouble than help.  There wasn't a ton of character development or back-story yet, which was fine because this is for middle school kids and it wasn't that long.  I'm sure as the series goes on we'll learn more about Dessa's past and more about her friends as the search for the chamberlain, who has disappeared at the end of the book, and try to find Dessa's brother.

I would definitely recommend this one for a middle school graphic novel collection.