Carl Tremarco is already regarded as a cult hero at Caley Thistle but the left back cemented his place in club folklore with a late winner that rounded off an otherwise forgettable 90 minutes.
Extra time and penalties loomed and, given Iain Vigurs had already missed from the spot in a turgid affair, little hope would have been held out for goals in the shootout either.
But a bit of ingenuity from 16-year-old Daniel MacKay – who scored for Scotland schools in a 2-0 win over England the night before – teed up the popular Tremarco to finally play the role of the hero.
Coll Donaldson made his return after a month out with a hamstring injury, starting in place of the suspended Brad McKay. Jake Mulraney was recalled to the team after missing out against Dundee United last weekend and replaced Charlie Trafford.
After missing two previous cup finals due to suspension, Gary Warren finally got his moment to lead Inverness out and he, more than anyone, deserves his medal.
He is a throwback to the Terry Butcher era and embodies what made that period of Caley Thistle’s history so successful. A team comprised of discarded players and lower-league gems, who were tempted up to the Highlands by the promise of top-flight football and an idyllic place to live.
Warren, who joined from Newport County in 2012, is one of the few remaining old heads. Relegation prompted a swinging scythe to the playing staff and finances but Warren remains, a rugged centre back who is only too happy to call Inverness home.
His clearance from Danny Handling’s cross was the first meaningful action in the game, with Caley Thistle content do dominate possession with Dumbarton taking their chances on the counter.
In attack, Caley Jags were toothless. George Oakley was reduced to grappling for hopeful passes forward and you could easily have forgotten Mulraney was playing.
As the second half wore on Caley Thistle grew more lethargic.
The introductions of Aaron Doran and MacKay at least drew a positive response from the crowd, who had been starved of virtually anything to cheer for.
Just when it looked as though the game might offer the sweet taste of salvation, it ripped it away again.
Doran’s cross was handled by Chris McLaughlin under pressure from MacKay with referee Andrew Dallas pointing to the spot. The omens were not good with Vigurs stepping up, given that he missed against Rangers from the spot last season and skewed horribly wide in the semi-final of this competition against Crusaders. Sure enough, he dragged the penalty low to the right and Scott Gallacher saved.
The game appeared destined for another 30 minutes of this but Tremarco made amends for his 2015 Scottish Cup final sending off when his red card almost cost Caley Thistle victory against Falkirk by becoming the hero on this occasion. MacKay, who made a huge difference after coming off the bench, fired across goal where Tremarco was waiting unmarked to crash the ball into the roof of the net. The neutral could not help but feel sorry for Dumbarton, who were out on their feet at the end. But there just seems to be something about Caley Thistle full backs scoring vital cup goals.
CALEY THISTLE (4-3-3) – Ridgers 6, Seedorf 6, Donaldson 6, Warren 6, Tremarco 6, Chalmers 5, Polworth 6, Vigurs 6, Bell 6 (MacKay 78), Mulraney 5 (Doran 70), Oakley 5. Subs not used – Esson, Calder, Elbouzedi, Trafford, Brown.
DUMBARTON (4-4-2) – Gallacher 6, Smith 6, Barr 6, Dowie 6, McLaughlin 6, C Gallagher 6 (Stewart 74), Carswell 6, Hutton 5 , Walsh 5 (Burt 81), Handling 6, Russell 6 (Froxylias 67). Subs not used – Burt, Wilson, Stewart, Hill, G Gallagher, Ewings.
Referee – Andrew Dallas
Attendance – 4,602.
Man of the match – Liam Polworth.