The controversial 30th minute sending-off of defender Stuart Whitehead left Darlington fuming and helped to ease promotion chasing Torquay towards another home win.
With the score at 1-1 Stuart Whitehead was dismissed for a professional foul when he appeared to pull down Torquay striker Martin Gritton.
Leicester referee Paul Danson produced the red card, despite protests on and off the pitch, before Alex Russell converted the penalty to give Torquay a lead they never gave up.
Darlington boss Mick Tait was furious about that incident and a free-kick which Mr Danson had given against his defender Simon Betts which produced Torquay's equaliser in the 22nd minute.
Irish striker Barry Conlon had volleyed Darlington in front in the 18th minute, but the free-kick against Betts four minutes later gave Gritton the chance to equalise with the faintest of touches.
Both Gritton and Barry Conlon have now scored 11 goals each this season.
"Two decisions have cost us the game," said Tait. "It was a diabolical decision against Betts and Stuart Whitehead says there was no contact when Gritton went down.
"Our supporters have come all this way to see 11 men play 11, and the referee has ruined it for them." There was no doubting the quality of Torquay's third goal in the 38th minute, defender David Woozley heading home after a classy eight-man move.
Even Torquay head coach Leroy Rosenior admitted that his side eased off in the second half, but he said: "We had done all the hard work in the first half." Darlington might even have salvaged something from the wreckage, but they made and missed good chances through Neil Maddison, Craig Liddle and Ashley Nicholls in the second half.