The Knights carried the play for much of the opening 20, and eventually hit paydirt after the Flames turned the puck over and were caught flat-footed in the neutral zone. With only one man back, Chandler Stephenson had a clear lane to the net. He sold the shot well, but dished off to Max Pacioretty, who cranked it through the wickets from the tops of the circles.
Shots on goal favoured the Knights 10-8 after one.
Markstrom had to be sharp, and single-handedly kept his team within striking distance thanks to a series of 10-bell stops.
First, he rejected a shot from Reilly Smith, who worked a give-and-go with William Karlsson off the rush, but a sneaky, left-pad save kept the game deadlocked.
Then, late in the period - and with the Knights applying pressure on the cycle - Karlsson fed the puck back to Jonathan Marchessault in the high slot, but his one-time offering was swallowed up by Markstrom, who moved his towering, 6-foot-6 frame to the top of the blue paint.
Markstrom was back at it in the second, robbing Smith (again!) on the doorstep, after a loose puck from a Marchessault flub landed right in the wheelhouse.
The Flames got their mojo going midway through the period when the Mikael Backlund, Milan Lucic and Andrew Mangiapane trio went to work in the trenches. The puck eventually found its way to Oliver Kylington, who had all kinds of time, walking it all the way in from the left point, but his wrister clanked iron and soared out of play.
Markstrom, though, continued to be THE story.
With under six to play in the stanza, Will Carrier showed great speed and turned a 50-50 puck into a clear-cut break. With Chris Tanev hounding him from behind, Carrier tried to chip it upstairs, but Markstrom made a solid stop to keep it a 1-0 game.
It was only the third time this season that the Flames trailed after 40 minutes.
The Flames had a great chance to even things up only seconds into the period, but Robin Lehner - who wasn't overly busy - made a good stop in tight.
The miss proved costly, as the Knights came right back and extended the lead.
Chris Tanev made a great play to disrupt a clean look from Shea Theodore, but the Vegas blueliner reset, settled the bouncing puck, and found a wide-open Nicolas Roy in the slot.
Markstrom had no chance as Roy went upstairs for his fourth of the year.
The Flames made a game of it at 9:19 when a Rasmus Andersson point shot was tipped home by Lindholm. Until then, the visitors were having trouble generating chances. Back-to-back shifts hemming the Knights in their own end nearly resulted in the equalizer, but Lehner stood tall.