Pilgrims playmaker Conor Hourihane provided the brightest moment of the first half with a thumping 30-yard opener in Tuesday night's West Country derby in League Two.
The 21-year-old Irish midfielder claimed his first Home Park goal after driving forward from the halfway line and letting fly with an unstoppable rising drive in the 35th minute.
A minute later, Argyle's on-loan Aldershot striker Guy Madjo's attempt at doubling the home side's lead was thwarted by Rovers central defender Tom Parkes.
Madjo had come close to opening the scoring when his long range shot hit the crossbar.
David Clarkson tested Argyle keeper Jake Cole with a seventh minute shot but that was the closest Rovers came to breaking the deadlock in the first half.