However, the Pilgrims will feel desperately disappointed not to have won the game against a Stoke side, who finished with ten men after goalkeeper Russell Hoult was sent off for a cynical professional foul.
Hoult, making his Stoke debut in place of the dropped Steve Simonsen, upended Sylvan Ebanks-Blake to deprive the Argyle striker of a clear run on goal and was shown the red card.
Ebanks-Blake had earlier netted his 12th goal of the season, levelling Stoke's opener when Argyle failed to deal with a long eighth minute throw-in and Richard Cresswell swept the ball home.
Moments after Ricardo Fuller had come within an inch of putting Stoke two up when he hit the post after some good skills, Stoke's on-loan Manchester United centre-back Shawcross handled to give away a penalty.
Shawcross' former Old Trafford team-mate Lee Martin was too quick for the defender who slid in impetuously and saw the ball hit his arm.
Ebanks-Blake's spot-kick was saved by Hoult, who flung himself to his left, but the ball sat up for Ebanks-Blake to fire it home.
After the interval, Liam Lawrence had a shot well saved by Argyle goalkeeper Romain Larrieu, but from Lawrence 's corner, Shawcross put Argyle left-back Lee Hodges under pressure and the defender deflected the ball into his own net.
Within ten minutes, the Pilgrims levelled by undoing Stoke from a set-piece.
Krisztian Timar powered home compatriot Peter Halmosi's in-swinging right-wing corner.
Argyle were lucky to stay on terms after Leon Cort deflected a shot by John Eustace to wrong-foot Larrieu, who saw the ball fly just wide.
Timar then sent Ebanks-Blake away only for the Argyle man to be brought down by Hoult, who was on his way before the referee even had the red card out.
Replacement Simonsen helped Stoke hold out under intense pressure, although man-of-the-match Ebanks-Blake nearly had the final say with an overhead kick from distance.