Milan Lucic found himself with the puck deep in the Montreal end and skated up to the right circle. From there, he dished the puck up to the high slot for Horton, who slid over to the right and slapped a shot that beat Carey Price cleanly for the win.
Boston moved on to face the Philadelphia Flyers for the second year in a row.
Canadiens fans will remember Chris Kelly's questionable hit on Roman Hamrlik when they think back on this one.
After a spear to Roman Hamrlik (and yes it was) Kelly made his way back up ice to cash a rebound past a sprawling Carey Price. Hamrlik remained on the ice for some time, hoping to gain the referees attention. Unfortunately the zebras, and even his own bench weren't buying it. Surprisingly, I'll have to quote our friend Jack Edwards and say that Hamrlik needed to, "Get up!" and get back in the play. The play was also controversial in that it was started by a high stick by Boston that wasn't called down.
They've got all off-season to remain annoyed by it now.