Ironically, it took Torquay just seven minutes to end a seven game League Two scoring famine when midfielder Lee Mansell drilled a low shot through a crowded goalmouth after Guy Branston only half cleared a corner by Adam Murray.
Posh were level within three minutes and then subjected the Torquay defence to a harrowing half hour when they conceded two more.
Shane Huke equalised, scoring his first goal for Posh from six yards on 11 minutes after a looping effort from Aaron McLean caused all sorts of panic in the Torquay goalmouth.
Then Adam Newton's vicious low right wing cross went into the net off the knee of emergency central defender Lee Thorpe on 25 minutes.
The Torquay defence again went missing as Mark Arber curled a 35th minute free kick to the far post and towering defender Ben Futcher comfortably beat goalkeeper Natham Abbey, who had been handicapped from the early stages by a leg injury.
Torquay still looked dangerous on the break and Chris McPhee brought the best out of Mark Tyler with rising effort that the home goalkeeper just managed to touch over for a corner.
The beleaguered Torquay defence was rocked by two more goals in a second half minute started by McLean's unstoppable header from Dean Holden's 59th minute corner. Then Richard Butcher strode forward to provide the finishing touch to a glorious move on the right involving Holden and McLean before a final cross by Adam Newton.
McLean limped off injured soon afterwards but replacement Trevor Benjamin was twice close to adding to the home tally before substitute Jordan Robertson, on loan from Sheffield United, made the score slightly more respectable for Torquay with a close range goal in added time.