It was close to being a horror story, but in the end it proved to be a fairytale.
Saints were lacking in inspiration before Harry Mallinder popped up to score a try on his European debut and ensure his club would fight on in this season’s Champions Cup.
In the only accurate attacking move of the match from either side, George North superbly palmed down Stephen Myler’s excellent cross-field kick for Mallinder to score.
It was an illuminating few seconds that lit up what had been another largely dull game at Franklin’s Gardens.
And it surely means Harry will be excused from buying his dad a Father’s Day present this year.
The try warmed the hearts of the Saints supporters who had braved freezing conditions to venture to the Gardens for an unusual Sunday evening encounter.
For 75 minutes, it looked like the efforts of those fans who had cleared snow from the pitch earlier in the day would see their hard work wasted.
But then a moment of madness from Glasgow - Tim Swinson’s punch on Mike Haywood resulted in a yellow card - and a moment of magic from Saints ensured the valiant volunteers could claim a part in a vital victory.
The Warriors had looked set to avenge their November defeat at Scotstoun with a gritty Gardens success.
Finn Russell had landed four penalties - and he should have notched a couple more - before Stuart Hogg stepped up to slot one which gave Glasgow a 15-12 lead.
But Swinson’s silly sin-binning and Saints’ long-awaited attacking masterpiece ensured it would be Jim Mallinder’s men who retained hope of making the quarter-finals.
It is still a tough ask, with a bonus-point win at Scarlets likely to be needed to make the last eight.
But at least Saints have a chance.
And they can be so thankful for that after failing to push on from Teimana Harrison’s early try in this game.
Saints were so dominant in the lineout drive that you felt they should have scored more than the two tries from it.
But they were hampered by the officiating, with Romain Poite allowing Glasgow to get underneath the mauls and stop them in their tracks.
The Scottish side were placing roadblocks under the Saints pack and they did well to overcome them for the Harrison and Christian Day scores.
That was the effective part of Saints’ game, along with the defending that saw them register their fourth successive shut-out at the Gardens this season.
In fact, Mallinder’s men have conceded just one try in six matches in all competitions on their own ground this season.
It is a stunning record and one which they should be so proud of, especially considering the repute of the opposition teams.
Saracens, Gloucester, Racing, Exeter and Glasgow have all failed to score a try against Saints at the Gardens, with Scarlets the only team to break them down.
That is a reason to be positive for the home fans, but they will rightly be disappointed about the attacking fare they have witnessed.
Because until Mallinder’s try, they struggled to look threatening with ball in hand, with half-backs Lee Dickson and JJ Hanrahan unable to find the spark that was needed.
The introduction of Myler and Tom Kessell helped turn the tide, and both will be pushing for starts in the must-win match at Scarlets on Saturday.
Saints will go to Wales in the final Pool 3 match with something to play for, and in a competition as tough as the Champions Cup that is an achievement.
But failing to make the quarter-finals would inspire plenty of frustration, especially considering the feeling that this team is capable of quality it has only shown in patches.
The 26-15 win at Glasgow in November showed what Northampton are capable of.
And they haven’t really been able to replicate that kind of attacking thrust since.
But they desperately need to this weekend if they are to keep the Champions Cup flame burning bright this season.
How they rated...
Moved to the wing when Collins went off and wasn’t really able to influence the game as he would have liked... 6
Didn’t have long enough on the field to make a big impact, but looked sharp early on as he used his pace to cause Glasgow problems... 6
A strong showing from the Samoan, who stood up to Glasgow well and was useful in defence... 6
Perhaps guilty of trying too hard at the moment, the centre is desperate to make things happen and occasionally fails to spot others because of his drive to score... 6
A great assist for Mallinder’s match-winning score as the winger finally found himself with a chance to shine... 6
Not the best of nights for the fly-half, who really struggled to command the game and was guilty of some uncharacteristic errors... 4
Put his body on the line for the team, but wasn’t able to give Saints the spark they needed in attack, with his box-kicking again annoying some supporters... 5
Plenty of appetite from the prop, who was strong throughout and didn’t do much wrong at all... 7
Hasn’t been able to get a run of games under his belt, but carried hard here and showed a desire to push his team forward... 6
Fought on after suffering an early knock and he celebrated his England call-up with a decent showing and a victory... 6
One of Saints’ more influencial figures as he carried the fight to Glasgow as well as doing his job defensively... 7
Got himself on the scoresheet and Saints’ second row always looks assured whenever he is part of it... 7
Never fails to impress and the flanker was a typically steady influence for Saints as he helped them defend well... 7
TOM WOOD - CHRON STAR MAN
Saints’ best player, the England star was hugely influential, dragging his team forward with some good runs as well as defending stoutly... 8
Another good showing from the December player of the month, who scored a first-half try... 7
Replacements (who played more than 20 minutes)
HARRY MALLINDER (for Collins 25)
What a moment for the youngster as he scored the winning try on his European debut. Before that, he had looked confident in the air... 7
MIKE HAYWOOD (for Hartley 57)
Added plenty of fire and desire as usual, and even took one for the team as he was punched by Tim Swinson at a pivotal point in the match... 6
JON FISHER (for Harrison 57)
Saints will be glad to see the big No.8 back and he added extra power to proceedings, pushing Glasgow back... 6