Montreal scored five power-play goals, four in the first period, en route to its third straight victory. The Canadiens have scored eight of their NHL-best 16 power-play goals in two games in Carolina, both wins.
Plekanec scored Montreal's first goal with the man-advantage at 8:40 in the first, and assisted on Alex Kovalev and Mark Streit's power-play goals in the period.
Kyle Chipchura, Saku Koivu and Mathieu Dandenault also scored, and Andrei Markov added three assists for Montreal, which has 17 goals in its last three games.
The Hurricanes, who had earned at least a point in nine of their first 10 games, couldn't keep up with Montreal's special teams after centre Jeff Hamilton cut the lead to 2-1 at 11:21 in the first.
Kovalev, playing in his 1,000th NHL game, made it 3-1 on Montreal's second power-play of the game at 12:20 of the first. Kovalev one-timed a crossing pass at the right circle for his fifth goal of the season and 338th of his 15-year career.
The Canadiens built a 5-1 first-period advantage when Carolina defenceman Mike Commodore scored on his own goalie, a goal credited to Montreal captain Koivu, and Streit finished the power-play spree with a goal with 1:24 left in the first.
The Hurricanes had a second-period goal nullified by matching roughing penalties at 13:55. A penalty shot by Carolina centre Eric Staal got the goal back at 14:46, which made it 5-2.
The Canadiens responded with another power-play goal, Plekanec's second at 16:20 in the second. The fourth-year Montreal centre entered the game with one goal and six points in the first eight games.
Carolina's Ray Whitney and Rod Brind'Amour scored in the third period.
Notes: Kovalev is the third Montreal player this month to play in his 1,000th game, joining Roman Hamrlik and Bryan Smolinski ... For the eighth straight game, the Hurricanes outshot their opponent. ... Carolina winger Erik Cole, who has 19 points in 19 career games against Montreal, missed his fourth straight game because of an ankle injury.