Thief's War — Hilari Bell

Knights errant aren't supposed to let the bad guy escape. But Sir Michael and his squire, Fisk, were up to their necks in mayhem (as usual) and Fisk's old mentor, Jack Bannister, quietly slithered away. Now Michael has tracked Jack to the notorious city of Tallowsport -- and it turns out Jack wasn't exaggerating when he said the crime boss he works for runs the town. With the Judicars and the Sheriff working for the bad guys, a lone knight errant aided only by his trusty squire and a pack of ragtag orphans shouldn't stand a chance. But the thing that really stands in Michael's way is that Fisk refuses to see his old teacher hang.