Grant McCann earned his second win as a caretaker manager and made it three unbeaten after a dramatic 4-3 win over Shrewsbury Town at the Greenhous Meadow.
Posh looked to be coasting at 3-0 up, but the home side came back to 3-3 just before the final whistle before Jon Taylor earned all three points against his former club four minutes into stoppage time.
Harry Toffolo, Adil Nabi, Leonardo Da Silva Lopes and Michael Smith were all named in the starting line-up and it turned out to an end to end contests.
Marcus Maddison produced a strong run from his own half in the early exchanges, but his left-foot shot went wide of the near post.
Baldwin was cautioned for a foul on the edge of the box on 18 minutes with Mark Tyler producing a fine tip over to ensure KaiKai's powerful free-kick didn't nestle into the back of the net.
Kaikai curled wide from 20-yards after Maddison was dispossessed on 27 minutes as the hosts came close to breaking the deadlock.
Maddison tested Halstead with a trademark swerving free-kick on 34 minutes after Whalley was cautioned for tripping Toffolo.
Posh should have had a spot-kick on 37 minutes as Maddison appeared to be tripped in the box, but referee Mr Salisbury waved away the protests with Halstead then beating away a drive from Da Silva Lopes.
Grant McCann's men opened the scoring on 42 minutes as an Adil Nabi corner kick was powered home at the back post by a towering BALDWIN for his first goal of his Posh career. Maddison then displayed superb skill to do a few tee-ups in the penalty area before his side-foot lob went inches wide.
In three minutes of stoppage time, goalkeeper Mark Tyler produced a stunning save to keep out a powerful drive from Mangan before Sadler volleyed over.
Posh doubled the lead within a minute of the second half, Maddison with a fine pass to Coulthirst, he cut inside, passed to ANGOL who slid the ball through the keepers' legs for his 10th goal of the campaign.
Posh made it 3-0 on 68 minutes and what a goal it was, some sharp football in the centre of the pitch and then Nabi burst forward and picked out ANGOL with a fine ball and the striker clinically fired across Halstead and into the bottom corner with his left-foot.
Jon Taylor replaced Nabi on 72 minutes and almost immediately, the hosts reduced the arrears as substitute Akpa AKPRO cut inside onto his right-foot and his curler took a deflection and looped over Tyler and into the back of the net.
Maddison was denied a fourth goal for Posh by a fine fingertip stop from Halstead moments later. Coulthirst was denied by Halstead after a good run from the lively Taylor down the left.
Callum Chettle replaced the excellent Forrester on 79 minutes as McCann made his second substitution. Maddison went close with a sublime chip and was then denied moments later by Halstead after being picked out by Angol.
The home side cut the deficit again on 86 minutes as a cross from the right was met by a powerful Andy MANGAN header which nestled into the net. Maddison was immediately denied by a fine Halstead stop diving to his right.
On 89 minutes, Shrewsbury incredibly made it 3-3 as Akpa Akpro's superb cross was headed home by GRIMMER.
Seven minutes of injury time was indicated by the fourth official as this incredible contest continued to shock and surprise. Four minutes into stoppage time, Posh made it 4-3 as Maddison picked out substitute TAYLOR, who fired low through the keepers' legs against his former club.
Black was then sent off for the hosts for a second booking following an aerial challenge on Toffolo.
Shrewsbury: Halstead Sadler, Whitbread, Whalley, Kaikai, Grimmer, Ogogo (sub Wallace 55min), Mangan, Knight-Percival, Cole (sub Akpa Akpro 55min). Unused subs: Wellens, Wesolowski, Hendry, Smith.
Posh: Tyler, Toffolo, Zakuani, Baldwin, Smith, Forrester (sub Chettle 79min), Nabi (sub Taylor 72min), Da Silva Lopes, Maddison, Angol, Coulthirst (sub Williams 86min) . Unused subs: Henry, Beautyman, Oztumer, Almeida Santos.
Half-time: Shrewsbury Town 0-1 Peterborough United
Full-time: Shrewsbury Town 3-4 Peterborough United
Attendance: 6,019 (494 Posh fans)