The lead did not last long, though, and the hosts were back on level terms with seven minutes of the half remaining when Craig Noone headed in from close range.
The Foxes dominated the chances after that, with Bruno Berner, Martyn Waghorn and Paul Gallagher all going close but failing to convert.
Leicester started encouragingly and created the first chance after three minutes when Gallagher's good low cross almost found Lloyd Dyer but Plymouth goalkeeper David Stockdale got down well to claim the ball.
The visitors' Matt Oakley almost threaded an inch-perfect through ball to defender Michael Morrison, who found himself in an attacking position, but Noone threw himself into a well timed sliding tackle to prevent the Foxes attack.
Reda Johnson had a chance for Argyle when but he lashed the ball wide of the upright after some good build-up play on the edge of the area.
Dyer thought he had put the visitors ahead on the half hour mark when he beat two men on the edge on the area before seeing his shot rebound wide of the upright and evade the waiting Waghorn in the six yard box.
Leicester took the lead just moments later when a long ball over the top looked to have beaten Waghorn's chase but Pilgrims defender Arnason failed to spot Stockdale coming off his line and diverted the ball past him and into the net for a calamitous own goal.
The lead lasted just seven minutes as the home side restored parity when Chris Clark delivered a deep cross and Noone arrived at the back post to head the ball past the helpless Chris Weale.
The first chance of the second period fell to Gallagher but his close-range effort was well blocked by Chris Barker as the second half started similarly to the first with the Foxes on top.
Waghorn was causing the defence all sorts of problems and from a difficult angle shot across the face of the goal only to see his shot drift inches wide as the Foxes looked to turn their possession into goals.
Richie Wellens almost engineered a chance after an excellent touch earnt him some space in the area but Damien Johnson lunged in to clear the ball before he had time to shoot.
The visitors continued to press forward and Berner should have given them the lead but he headed Gallagher's cross wide of the upright from a yard out.
Source: Team Talk
Source: Team Talk