Star number one was goalkeeper Wayne Henderson, once on County's books. He produced a string of outstanding saves in the first 45 minutes when Notts had no fewer than seven goal attempts on target.
The first was from Richard Butcher, who burst into the box in the 16th minute, looking for his eighth League goal of the season, only to be denied by a good block.
Ten minutes later, a thrilling volley by Matt Hamshaw was saved by Henderson and, four minutes after that, as Notts swarmed through again, he made an outrageous double save to keep out efforts by Butcher and Myles Weston.
Henderson's last contribution of the first half was one he probably knew little about when some part of his body got in the way of a Jonathan Forte rocket.
What a different story it was in the second half, in the sixth minute of which the Mariners forged ahead to the delight of nearly 2,000 travelling fans.
Peter Sweeney's left-wing corner was sharply headed through by central defender Rob Atkinson, who buried the ball low in the far corner.
A second goal on 79 minutes completed County's utter discomfort and assured the Mariners of the three vital points - and it was not without controversy.
Receiving an astute ball from Barry Conlon, Danny Boshell shot past Kevin Pilkington, but his celebrations were cut short by a raised flag for offside.
The referee was persuaded to consult his official and they apparently agreed, but it was not Boshell but another Grimsby player who was standing offside and the goal was allowed to stand.
In later exchanges Notts never seemed likely to break down an increasingly resilent and confident Grimsby rearguard.