Teimana Harrison scored a hat-trick as Saints produced a showing full of character against French giants Clermont Auvergne in a crazy Saturday night game at Stade Marcel Michelin.
Chris Boyd's men were eventually beaten 48-40, but they secured a try bonus point, registering six times against the Top 14 table-toppers in a rollercoaster Challenge Cup clash.
Clermont, the only team with a flawless record in this season's European competition going into the game, had gone ahead early on, issuing an ominous warning.
But Saints soon set the tone for their night's work with a rapid, determined response.
Tries from Fraser Dingwall and Alex Mitchell put them ahead, before Clermont roared back to score two of their own before the break, earning a 27-12 half-time lead.
But if the first half was wild, it was nothing compared to the second as Saints refused to be deterred and roared back into contention thanks to four further tries, three of which came from Harrison.
Cobus Reinach also registered and twice Clermont were just a point up, at 34-33 and 41-40, but they eventually finished things off thanks to a Remi Grosso try.
It was an incredible European encounter, with Saints, who did see some calls go against them, so unfortunate to only take one point from the game.
They had to bounce back early on as Clermont emerged with real swagger, cranking up the heat, with Damian Penaud's offload opening the door for lock Sitaleki Timani to score.
Morgan Parra placed the conversion between the posts and the home supporters lifted the decibel levels in traditional fashion.
But Saints were not fazed and they came straight back at Clermont, scoring a try that was most definitely made in Northampton.
Dingwall looped a long pass out to Tom Collins and after the wing sped towards the line, he offloaded for the supporting Dingwall to score in the corner.
Dan Biggar just missed the conversion from the touchline, but Saints were soon ahead.
It was another great moment for the Academy as two more graduates combined, with hooker James Fish breaking the line and scrum-half Mitchell taking the offload to score.
Biggar converted but he had picked up an injury that was to prove costly soon after.
After Saints almost scored through Heinrich Brüssow in the corner, Peceli Yato made the most of an interception in the home 22 and sprinted to the line, with the limping Biggar unable to catch him.
Parra converted and Clermont were back in front.
Biggar soon had to go off, and Clermont were also forced into a couple of early changes, with Penaud and Julien Cancoriet injured.
The game was being played at a frantic pace but the scoring slowed a little before the lively Brüssow gave away a penalty after a scrum, and Parra kicked to put his team 17-12 up.
Saints were troubling Clermont every time they got their hands on the ball, but the same could be said the other way around as the home side looked strong and determined in possession.
After Dingwall was unable to make a tackle close to halfway, Clermont worked the ball well, allowing former Leicester back Peter Betham to score.
Parra missed the conversion, but Clermont soon had their bonus point as Wesley Fofana slalomed in from the left, beating Brüssow to score.
Parra converted and the hosts held an ominous 27-12 lead with five minutes of the first half remaining.
Taqele Naiyaravoro tried to burst into life in response, picking the ball up at the breakdown and flying forward before eventually losing the ball.
A breathless first half was to end with a 15-point deficit for Saints, who had been sharp in attack but outgunned in defence by a sizeable Clermont side.
After a crazy kit clash, with Clermont wearing dark blue and Saints sporting their black home strip, a change was made at the break, with the home side switching to white shirts.
And Saints came out of the blocks the quickest as they were unlucky to be denied a Mitchell try by what appeared to be a high tackle before justice was done.
The visiting pack, and a couple of the backs, turned on the power from a lineout drive and Harrison profited to score.
Clermont came straight back at Saints with Yato offloading brilliantly to allow Fofana to grab his second five-pointer of the night.
Parra converted, but Saints responded again as Collins sent Harrison away out wide and the No.8 turned into a top winger as he sold a dummy to bag his team the bonus point.
Grayson converted to cut the gap to eight points once more and Saints flew forward in search of more with Collins and Dingwall almost combining for another score.
Clermont just managed to survive thanks to another penalty awarded at the breakdown by referee John Lacey.
But their reprieve was only temporary as brilliant offloads from Luther Burrell and Lewis Ludlam, who had just come on, set up the onrushing Reinach, with the scrum-half making an instant impact with the score.
Grayson converted again but in a see-saw game Clermont were straight back in Saints' faces, proving simply too strong in attack as Betham finished another flowing move.
Parra converted again and it was a real blow for Saints as they saw the one point gap extended to eight once more.
But Saints would not go quietly and Harrison grabbed his hat-trick score before Grayson drew more roars from the travelling support with the successful conversion.
However, every time Saints got to within touching distance, Clermont found something extra, with Grosso evading Andrew Kellaway, who was on for Ahsee Tuala at full-back, to score.
Patricio Fernandez converted to take the losing bonus point away from Saints, but they deservedly took the acclaim of the travelling fans at the end of a frenetic night in France.
Clermont Auvergne: Betham; Penaud (Lamerat 8), Moala, Fofana, Grosso; Lopez (Fernandez 77), Parra (c) (Laidlaw 65); Falgoux, Kayser, Zirakashvili (Falatea 77); Timani, Vahaamahina; Iturria, Cancoriet (Chouly 11), Yato.
Saints: Tuala (Kellaway 70); Collins, Dingwall, Burrell, Naiyaravoro; Biggar (Grayson 10), Mitchell (Reinach 55); van Wyk (Waller 64), Fish (Marshall 57), Painter (Franks 62); Ribbans, Ratuniyarawa (Wood 65); Lawes (c), Brüssow (Ludlam 55), Harrison.
Referee: John Lacey