Luton striker Carlton Morris scored against the club where he began his career as Norwich City suffered their third successive Championship defeat.
Morris, signed from Barnsley in the summer, placed his seventh goal of the season beyond Angus Gunn after a couple of slick step-overs to deceive defender Grant Hanley as the Hatters stretched their unbeaten run to seven games.
And Norwich went down to 10 men four minutes later when Scotland international Kenny McLean was shown a straight red card after appearing to raise an arm to Tom Lockyer.
Teemu Pukki whistled a shot past the post as the Canaries pressed for an equaliser, but there was no way back for Dean Smith's side as they slipped two places to fifth in the table - below Luton, who moved up to fourth.