The County endured a nightmare evening at Old Trafford as they were taken apart, with the rampant home side winning with more than four overs to spare.
The Steelbacks were outclassed and overpowered in every department, struggling to 142 for eight after winning the toss before the bowlers were given a pummeling as Lightning powered to 144 for two in 15.4 overs.
Finn Allen hammered 66 from 37 balls and Keaton Jennings 54 not out from 41 balls, and the defeat leaves Northants three points off fourth-place Lightning with two matches to play.
Rob Keogh was the only batsman to get to grips with things for the Steelbacks, hitting 56 from 48 balls, with Northants never recovering from slumping to eight for two in the first two overs, and then 36 for three by the end of the powerplay.
They then lost four wickets for just eight runs at the end of their innings on what was a night to forget.
The Steelbacks were unchanged from the win over Durham, but there was to be no repeat performance from opening batsman Ben Curran, who hit a maiden T20 50 in that game.
This time he lasted a couple of balls before hitting spinner Steven Croft down Alex Davies' throat at deep mid-off to go for one in the first over the match to leave the Steelbacks three for one.
Things got even worse a few balls later as the in-form Ricardo Vasconcelos departed as he also decided to hit the ball straight to a fielder, this time picking out Croft at deep mid-wicket with an attempted slog sweep off the bowling of Tom Hartley.
Two overs in, the Steelbacks were eight for two.
Skipper Josh Cobb and Rob Keogh got things moving, but in the fifth over the Steelbacks were dealt a huge blow when the captain went for 20 from 17 balls.
He had just hit successive boundaries but then perished going for a third, clipping pace bowler Liam Hurt straight to backward square-leg and Northants were 36 for three.
By the end of the powerplay the Steelbacks 41 for three, and with a lot of work to do.
Keogh and Mohammad Nabi decided it was best to work the ball about without taking any risks, and by the halfway stage they had reached 67.
Somebody was going to have to open up if the Steelbacks were going to set a testing total for their hosts, and Nabi decided the 12th over was the time to do just that as he hit Hartley straight back over his head for the first six of the innings.
But he didn't get the chance to build on it as he was out in the 13th over, as he missed a straight one to be pinned leg before to Danny Lamb and Steelbacks were 96 for four, with Nabi and Keogh having put on 60.
Keogh hit his first six of the innings off Luke Wells as the Steelbacks reached the end of the 15th over on 116 for four, and in reasonable shape.
Northants needed to put their foot down in the closing overs, but that was proving easier said than done against some tight bowling.
Keogh brought up an excellent 50 from 41 balls, but going into the final three overs the Steelbacks still looked under par at 129 for four.
Zaib had struggled for timing and was out for 11 as he top-edged an attempted big hit off Luke Wood.
Boundaries of any kind were still proving elusive and as the Steelbacks tried to hit them, they then lost wickets in dramatic fashion as they slumped from 130 for four to 142 for eight at the close.
For Lightning, Hurt finished with three for 22.
The Steelbacks needed a good start with the ball, but they didn't get it despite Nabi's opening over only going for a single.
Alen and Jennings quickly found their range, hammering a series of fours and sixes as the home side finished the powerplay on 56 without loss, with the Steelbacks under the cosh and ragged in the field.
The easing of fielding restrictions didn't slow Lightning's progress as the runs continued to flow at an alarming rate, and the game was as good as over after nine overs as the home side raced to 87 without loss.
The Steelbacks did pick up a couple of late wickets, but there was no way back into the game as Lancashire kept alive their hopes of reaching the quarter-finals and all but ending those of Northants.
With the ball, there were wickets for Nabi and Freddi Heldreich who finished with one for 26 and one for 20 respectively from their four overs, but the rest of the figures were not pretty.