James Wisniewski assisted on both power-play goals. He set up Hamrlik's tying goal 13:19 in and Plekanec's 14th goal, which made it 2-1, at 14:50. Andrei Kostitsyn scored Montreal's final goal at 16:03.
"I think we might have sat back a little bit, and then they kind of took it to us a little bit," Wisniewski said. "We were protecting the two-goal lead instead of keeping our pedal to the metal, but the main thing is we got away with two points."
Carey Price made 31 saves for the Canadiens, who beat the Rangers 2-1 in New York on Tuesday. Montreal, which lost to Pittsburgh on Thursday, is on a 5-1-1 run.
Mats Zuccarello drew the Rangers within one 6:57 into the third. Brian Boyle, who scored his 15th goal, was denied from netting the tying goal moments later on a pad save by Price. The Canadiens goalie also made a sprawling stop on Wojtek Wolski's backhand with less than five minutes remaining.
"They were hot in the third period," said Price, who made several more stops in the final minute after Montreal defenseman Hal Gill was called for hooking Boyle behind the Canadiens net with 1:05 left in the third. "They did an excellent job of running the play down low and creating their opportunities off of that. I think that's the strength of their hockey team."
Henrik Lundqvist stopped 38 shots for New York, which had scored just one goal in each of its previous two games -- including a 1-0 win Thursday over NHL-leading Vancouver.
The Rangers, who fired 21 shots in the third, were outshot 41-33 overall, including 16-6 in the first and 13-6 in the second.
"I'm not sure what it's from -- from a hard game against Vancouver, I don't know, it just took us a couple of periods to get going," Rangers coach John Tortorella said. "They're a quick team but we never got near a puck. We were just so slow in the third period. I felt we got our legs underneath us and got to the game that we need to play, and that's chip 'em in and grind and try to hold your neutral zone. It wasn't just one person in the first two periods, it was our whole group. We just looked slow."
Hamrlik drew Montreal even at 1 with his fourth goal after New York's Brandon Dubinsky was sent off for roughing. The veteran defenseman drove a slap shot from the point that struck Rangers defenseman Dan Girardi on its way past Lundqvist.
Mike Sauer was serving New York's second penalty for tripping 1:31 later when Plekanec put the Canadiens up 2-1. The Montreal center stopped P.K. Subban's pass with his right skate and snapped a shot into the right side of the net.
Kostitsyn increased the lead to 3-1 with his first goal in 10 games. He drove to the slot and one-timed Jeff Halpern's pass into the top of the net for his 11th goal, and first since Dec. 23.
Lundqvist drew a roughing penalty at 17:40 of the second after he jumped on Max Pacioretty and threw a punch with his blocker.
"I loved it," Tortorella said. "I thought it was terrific. I loved his emotion."
Pacioretty, who was pushed into Lundqvist by Dubinsky, was penalized for roughing and closing his hand on the puck. Dubinsky and Montreal captain Brian Gionta were also given roughing penalties.
"Hank has taken his fair share of guys running him over in the crease," Dubinsky said. "He got run over and took exception to it, and a pile-on ensued. It just shows the passion that he plays with and how much he cares."
Boyle gave the Rangers a 1-0 lead 6:58 in when he jammed home a loose puck in the crease from the side of the net.
- Tortorella used his timeout before a faceoff in Montreal's zone with 1:22 remaining.
- Canadiens LW Mike Cammalleri returned after missing two games because of strep throat.