Plymouth lost top spot in Sky Bet League Two as a superb defensive display saw Barnet hold on for a 1-0 win at The Hive.
The Bees took the lead in the 14th minute, with the diminutive Mauro Vilhete sending Nana Kyei's corner looping in at the far post.
Kyei almost put the Bees two up when he raced past his man and into the box, only for goalkeeper Luke McCormick to produce a fine save.
Barnet flew out of the blocks after the break, with John Akinde denied by McCormick before Kyei clipped the crossbar.
Argyle's Paul Garita headed over from close range but Michael Nelson and Ricardo Santos weathered the storm in the middle of the Bees' defence.
Vilhete nearly made the points safe with eight minutes left but McCormick produced another one-on-one save.
And Gary Miller should have brought Plymouth level seconds later, only for the Scot to volley wide from five yards as Barnet held on.