Argyle ace Simon Walton fired the home side ahead from a 21st-minute free-kick from the left following a foul by Dons central defender Sean O’Hanlon on lively home winger Yannick Bolasie.
Walton – a revelation since returning from injury – swung in his free-kick from 25 yards and the flight deceived Dons goalkeeper David Martin, as well as eluding recalled Plymouth striker Rory Fallon.
Dons must have wondered how they did not equalise six minutes later. Daniel Powell’s thumping strike sent home keeper David Button the wrong way but the on-loan Tottenham man managed to keep the ball out with his trailing leg. The ball then fell kindly to Angelo Balanta, whose follow-up strike was cleared off the line by Argyle right-back Karl Duguid.
Martin made a superb save to keep out Kari Arnason’s 74th-minute angled drive and then denied Bolasie as he broke through on goal with just the keeper to beat.
In the fourth and final minute of stoppage time, Bolasie broke free and smashed a shot off the Dons crossbar.