Down the Mountain to Collect a Debt, Got a Wife Instead

Xiao Yang descends from his mountain training with a single mission: collect the debt his master is owed. Armed with nothing but an old IOU from a Taoist priest, he expects money—but discovers the "debt" is actually a bride. One moment he's a debt collector, the next he's a husband. How did chasing down what he's owed land him in this arrangement?