Scarborough freshman Wyatt Grondin entered the boys’ hockey postseason a relative unknown.

Now, he’s a legend, and the Red Storm are improbable Class A state champions.

Saturday afternoon at Cross Insurance Arena, Scarborough completed its rise from the No. 7 seed, as Grondin scored his third overtime goal of the playoffs to give the Red Storm a 2-1 double-overtime victory over No. 5 Thornton Academy.

Scarborough got an early goal from Will Fallona, held the lead well into the third period thanks to goalie Keegan Weed, then regrouped after Thornton Academy drew even on a goal by Evan Beaudette.

Scarborough won its third state championship, and first since 2015.

“It’s just amazing,” Grondin said. “I’m just so happy to win it for the seniors.”

“I’m just tremendously grateful to be part of this program,” added Scarborough’s first-year coach, Eric Wirsing. “This group of kids in the locker room, throughout the year, just believed in what we wanted to accomplish.”

Scarborough (13-8-1) tested Thornton’s talented goalie, Gage Tarbox-Belanger, from the get-go, and while he saved the first three shots he faced, the Red Storm broke through at 2:57 when Fallona poked in the rebound of a Sam Rumelhart shot.

Thornton didn’t muster a shot for nearly 10 minutes, but then started testing Weed, who preserved the 1-0 advantage going into the first intermission.

In the second period, both goalies made 10 saves.

Scarborough came out strong again, but Tarbox-Belanger turned away bids from Fallona, Daemon Bobbin and Jack Matthews.

The Golden Trojans then got good chances from Alex St. John and Beaudette, only to be denied by Weed.

Thornton finally broke through with less than six minutes remaining in regulation.

After Weed made a great glove save on a St. John blast, then stopped two shots by Colby Bilodeau, but Beaudette converted a rebound at 9:18 to make it 1-1.

The Red Storm had a power-play opportunity moments later, but Tarbox-Belanger made saves against Jack Matthews, Olin Pedersen, Bobbin and Matthews.

The Golden Trojans peppered Weed in the first eight-minute overtime, but he robbed St. John only five seconds in, and after St. John twice missed just wide, Weed stopped a shot from Kyle LeSieur.

Two other chances by St. John were turned aside by Weed.

“From the second period on, we were a much better hockey team,” said Thornton Coach Jamie Gagnon. “We played our game as opposed to sitting on our heels.”

After Matthews missed just wide in the waning seconds of the first overtime, the teams took a break for the ice to be resurfaced.

In the second OT, Grondin joined Sean McGovern (2015) as players to score a state championship-winning overtime goal for Scarborough, as he redirected Rumelhart’s shot past Tarbox-Belanger at 3:05.

“When I saw Sam’s shot was going wide, I just tried to redirect it on net,” Grondin said. “It was crazy when it went in. So fun.”

“Wyatt’s always in the right spot,” added Rumelhart. “He always finishes when we need him to.”

Weed finished with 27 saves.

“My goal coming in to this game was to play the best hockey I could for my team,” said Weed. “Winning a state championship is just an amazing experience.”

Thornton (15-6), which never went on the power play (Scarborough was 0 for 1), got 30 saves from Tarbox-Belanger.

“We got in a hole early and (Weed) played really well, but we fought back and played well in overtime until that last shot,” said Gagnon. “We know in overtime, it’s going to be a tip or a deflection that wins it.

“I thanked the seniors for everything they’ve done. They’ve laid the foundation for our program going forward. The way they played and the way they led, I couldn’t ask for anything more.”