SummerSlam 2012 was mainly built around Brock Lesnar's surprising return the night after WrestleMania 28. After losing to John Cena, Lesnar made it known that he was the one who lorded over his WWE tenure. At the time, John Laurinaitis was the general manager of Raw. Lesnar bullied Laurinaitis to approve the outlandish conditions included in his contract.
However, Triple H had to come in to stop the tyranny.
This led to Paul Heyman being involved, Lesnar executing a Kimura lock (kayfabe) to break HHH's arm and a match finally being agreed upon for SummerSlam.
During John Laurinaitis' reign as GM, both CM Punk and John Cena fell victim to mistreatment.
Punk overcome the odds and continued his long title reign, but Cena was forced to defy the odds throughout the year. Cena lost to Laurinaitis at Over the Limit but defeated Big Show at No Way Out to dethrone Laurinaitis from his position. However, the Cena/Big Show feud did not end, and they both were vying for the WWE title.
A month before SummerSlam, a year into his WWE title reign, CM Punk shocked the WWE Universe by turning heel as a result of applying his GTS on the Rock at the Raw 1000 episode. This led Punk to accuse the WWE Universe for not respecting him, and he vowed to prove why he should be the top billing of the company.
At the PPV, Punk managed to escape with a victory after throwing Cena outside following an AA to the Big Show. He remained champion until Royal Rumble 2013.
World Heavyweight Championship
After winning the 2012 Royal Rumble, Sheamus went on the defeat world heavyweight champion Daniel Bryan in 18 seconds at WrestleMania 28. Prior to SummerSlam, he would go on to successfully defend the title against Randy Orton, Chris Jericho, Alberto Del Rio and Dolph Ziggler.
Alberto Del Rio earned a shot at the WHC heading to the No Way Out PPV, but he was replaced by Dolph Ziggler as a result of suffering a concussion.
As SummerSlam, Sheamus managed to retain the title, but in an odd way. After a hard-fought match that also involved ADR's personal ring announcer Ricardo Rodriguez, Sheamus applied his Irish Curse backbreaker and won the match after removing Del Rio's foot from the bottom rope. The referee did not see his foot on the rope, and the decision remained.
Other Notable Matches
Brock Lesnar d. Triple H
Chris Jericho d. Dolph Ziggler
Miz d. Rey Mysterio: Intercontinental Championship