Wanderers’ long unbeaten home run came to an agonising end as their attempted fightback came up short.
Trailing to a headed goal from Macauley Gillesphey just before the break, the Whites did everything but score in a final half hour in which they threw everything at an Argyle side fighting to stay in the top six.
But with Plymouth goalkeeper Michael Cooper proving unbeatable, the visitors held out to secure a huge win for their promotion prospects and leave Wanderers 10 points adrift of the play-off places with just eight games to go.
Cooper somehow kept out point-blank efforts from Dion Charles and the returning Elias Kachunga as Ian Evatt’s men gave everything to try and keep their challenge alive.
But nothing went their way in the penalty area – before or after half-time – and as Cooper proved a magnet for the ball Wanderers were unable to find a way through to avoid a first home defeat since mid-January.
Jon Dadi Bodvarsson earned a start for Wanderers following his mid-week equaliser against Morecambe which had extended the Whites’ unbeaten home run to seven games.
And the Icelander was involved in many of Wanderers’ best moments of a cagey first half in which it felt vital to strike the first blow.
Twice he led breakaways which ended with shooting opportunities for Dapo Afolayan and Charles.
But neither managed a clean strike on target and when Bodvarsson went close himself with a header from an Aaron Morley corner, Plymouth counter-attacked to create their first real chance.
Ryan Hardie got away down the right-hand side and from his fine low cross, Niall Ennis just failed to get enough of a touch to beat James Trafford.
Trafford then saved from Hardie after Argyle’s leading scorer had run onto a free-kick from James Wilson and it took a timely block from Wanderers’ skipper Ricardo Almeida Santos to snuff out another opening for Hardie.
The visitors’ pressure was beginning to grow, though, and two minutes before the break they grabbed the lead when a corner delivered beyond the far post was headed home by Gillesphey.
That goal left Wanderers needing a big second 45 minutes and in a passive start they were nearly punished when Ennis was allowed to wriggle free and pick out Joe Edwards for a shot blocked on the line by Santos.
It needed a spark of inspiration from somewhere and Afolayan looked to provide when he played a one-two with Bodvarsson before forcing Cooper into a scrambling save to set the tone for the final 30 minutes.
Afolayan then moved out wide as Evatt changed formation and personnel with Kieran Sadlier given time from the bench to make his mark.
The substitute brought a fresh energy and within minutes of Sadlier’s arrival Wanderers were almost level when MJ Williams found space to deliver the ball into the near post where Charles connected with a header which Cooper somehow kept out at point-blank range.
Wanderers were beginning to stretch the Argyle defence again as an equaliser looked increasingly likely and Evatt played his final card with a double change with some 20 minutes to go as Amadou Bakayoko and the fit-again Kachunga came on.
Kachunga hadn’t featured since the turn of the year but with his first touch he – and the whole of the stadium – thought he had made it 1-1.
Afolayan’s lovely cross found Kachunga at the far post and Cooper knew nothing about the downward header which struck his leg and the post and somehow bounced to safety.
Bakayoko then had a chance from a Sadlier cross he clipped at Cooper as Wanderers tried to overcome a succession of stoppages to keep the momentum going.
Marlon Fossey was among those to go down injured and with a couple of minutes of regulation time left he finally had to succumb to leave Wanderers to try and rescue something with 10 men for the seven minutes of added time.
Those were extended as Plymouth continued tried to eat up time and almost doubled their lead as Hardie was denied by Trafford.
And with Wanderers unable to conjur up a late leveller for the second game in a row, they were left to rue more missed chances which have proved costly in a return of four points from the last four games at a critical time.
Wanderers: Trafford; Aimson, Santos, Johnston (Sadlier 58); Fossey, Williams, Morley, John; Afolayan; Charles (Kachunga 72), Bodvarsson (Bakayoko, 72). Substitutes: Dixon, Amaechi, Thomason, Baptiste.
Plymouth: Cooper; Wilson, Bolton, Gillesphey; Edwards, Broom (Camara, 69), Houghton, Mayor, Grant (Sessegnon 81); Ennis (Jephcott, 81), Hardie. Substitutes: Burton, Garrick, Randell, Chrichlow.
Referee: Robert Lewis
Attendance: 16,078 (Plymouth 1,356)