Saints saw their 13-match winning streak crushed as fired-up Exeter Chiefs used home advantage to claim a 15-8 LV= Cup final success.
Tries from Chris Whitehead and captain Dean Mumm, allied with five points from the boot of Henry Slade made it four final defeats in as many years for Northampton.
Glenn Dickson, who came into the side for Stephen Myler, a hamstring injury victim in the build-up to the game, landed a first-half penalty and Samu Manoa scored late on, but it wasn’t to be enough.
The Chiefs, roared on by a sizeable amount of fans at their Sandy Park ground, were almost an inexorable force, helped by the continual offending of their opponents.
Saints had been impressive on their way to racking up the fine sequence of wins, but this was their poorest performance since the defeat to Leinster back in December.
And, to their credit, Exeter used everything they were given to good effect, showing huge aggression at the breakdown, with high linespeed forcing errors from their opponents.
It meant that as the Chiefs lifted the LV= Cup for their first time in their 143-year history, on the club’s biggest day, Saints were left to set their sights on two more chances of silverware.
The Aviva Premiership and Amlin Challenge Cup still provide realistic trophy chances, with Northampton back up to full strength following the return of their Six Nations stars.
They had won seven successive games since the England players and George North departed, but an eighth win, and the silverware it would bring, proved to be elusive.
The loss of Myler before kick-off got things off to a bad start and it got worse when the game began as Whitehead made the most of a huge lineout drive to score.
Slade sent his conversion to the left of the posts before Dickson was handed his first test from the tee after Saints smashed Exeter in the scrum.
The Kiwi kicker sent his effort through the posts to cut the deficit, but Exeter were still dominating territory and possession.
Kahn Fotuali’i was doing his best to turn the tide in Saints favour, with box kicks and sparky play around the fringes helping his team wrestle back some momentum.
Saints were knocking loudly on the door, but Exeter resisted bravely, first from a lineout drive then from a series of scrums five metres from their line.
The men in blue were looking sharp at both ends of the pitch, with Saints desperately trying to match the intensity.
Two penalties were conceded in the space of as many minutes, with Chiefs fly-half Slade missing the first but slotting the second.
Saints were desperate to get a grip on proceedings, but errors were costing them dear and Exeter’s high linespeed was proving hugely effective.
The Chiefs held an 8-3 lead into the break, after a first half in which very little had gone the Northampton way.
The second period continued in the same vein as Saints shipped a series of penalties which saw them give Exeter the respite they needed.
That allowed the Chiefs to continue to build the platform they required and, 10 minutes into the second half, they had a score that looked to take the game away from Saints.
Skipper Mumm latched on to an inside pass and powered over the line, pumping his first in delight as he hit the ground.
Slade’s well-struck conversion took the score to 15-3 in favour of Rob Baxter’s side and Saints needed something special in the final 30 minutes of the game.
But still Exeter continued to dictate proceedings and it took a fine saving tackle from Ken Pisi to deny full-back Luke Arscott another try.
Saints were desperate for some inspiration and finally they got it as the ball was sent wide by Christian Day and Manoa grabbed his 10th try of the season.
Dickson sent a tricky conversion wide in the wind and Exeter still held an eight-point lead going into the final nine minutes.
But, hard as they tried, Saints couldn’t break the blue resistance for a second time, with a final surge stopped by some more heroic defending.
The Chiefs fans who filled Sandy Park were left to party long into the night, while Saints returned to the drawing board in search of a trophy that would end their four-year wait.
Exeter Chiefs: Arscott; Vainikolo, Dollman, Shoemark, Jess; Slade, Lewis, Moon, Whitehead (Cowan-Dickie 66), Tui (Brown 66); Mumm, Welch; Ewers, White (Armand 50), Horstmann.
Replacements not used: Rimmer, Graham, Thomas, Steenson, Naqelevuki.
Saints: Foden; K Pisi, G Pisi, Wilson, Elliott; G DIckson (A Day 74), Fotuali’i; A Waller (E Waller 64), Haywood, Ma’afu (Mercey 49); Manoa, Day, Clark (Nutley 50), Dowson, van Velze.
Replacements not used: McMillan, Craig, Olver, Autagavaia.
Referee: Andrew Small