Barney Ross, the leader of the mercenary team known as the Expendables, is approached by CIA agent Mr Church who proposes a new mission for Ross; to go with the Expendables to Albania and retrieve a briefcase from a crashed airplane. Ross declines, but Church threatens to turn Ross over to the CIA if he does not comply. Reluctantly, Ross assembles the group and they leave for Albania.
They are met by technical expert Maggie Chan, who was sent by Church to crack the safe the briefcase is held in. They manage to locate the plane and retrieve the case, while Ross' old friend Tool keeps a look out. Returning from the crash site, the group finds themself surrounded by an opposing mercenary group. These are revealed to be the Indestructibles, led by Claude Vilain. With Tool as a hostage, Vilain forces them to hand over the briefcase. The team comply and Vilain departs in a helicopter, but before he goes, he throws a knife into Tool's back, killing him. After burying Tool, the Expendables decide to follow Vilain and get revenge.
Maggie reveals that the case contained a computer which held the secret location of five tons of weapons grade plutonium. The plutonium was found in a mine which was abandoned by the Soviet Union following the end of the Cold War. Ross becomes determined to kill both Vilain and Church in retaliation, but Maggie reveals that Church has come under great pressure from fellow agent Max Drummer, and had no choice but to call Ross in.
The Expendables are able to track the computer's weak signal and wind up at a deserted military base, where they sleep. The following morning, they are ambushed by armed militia and a firefight ensues. The group eventually become pinned down until they are rescued by Booker, a former soldier and Ross' old friend. Upon investigating the bodies of their attackers, Ross realises that they aren't members of the Indestructibles, and concludes that they were sent by Church to kill the rest of the Expendables. Booker accompanies the group to a nearby village, where there lives only women and children. It is revealed that the Indestructibles kidnapped all of the men in the village and forced them to work as slaves in the mine. Meanwhile, Vilain and his right hand man Hector have found the plutonium and begun collecting it.
A group of Indestructibles arrive in the village to collect more villagers, but are ambushed by the Expendables and killed after a firefight. They then locate the mine and infiltrate it. However, Vilain has already retrieved all of the plutonium and he blows the mine before brutally murdering the remaining miners with a machine gun. The Expendables survive, but are trapped in the mine. They are rescued by Trench Mauser, another mercenary and Ross' friendly rival, who takes them to Church. Ross is ready to kill Church, until he reveals that he didn't send the men after them. He also offers to help the Expendables in getting revenge for Tool.
Villain and the Indestructibles storm into an airport, where they are going to sell the plutonium to a mysterious benefactor. The Expendables intercept them and are shocked to find that the buyer is none other than rogue agent Max Drummer. A large firefight erupts between the Expendables and their allies and the Indestructibles. Lee Christmas, the team's knife expert, engages Hector in a one on one fight and kills him by punching his head into the rotory blades of a helicopter. Church and Mauser fight side by side, until Church mysteriously runs off. Mauser is then shot in the knee by Drummer, who prepares to execute him. Suddenly, Church crashes in driving a stolen jeep and runs Drummer down. Mauser climbs into the jeep and they tear through the Indestructible forces.
Ross pursues Vilain, who is trying to escape, and engages him in a brutal hand to hand fight. The battle is bitter and relentless, leaving both men badly beaten and bloodied. Just when it appears that Vilain has gained the upper hand, Maggie appears and tosses Ross a grenade belt, which he then wraps around Vilain's neck before pulling all of the pins out. Vilain dies when the grenades explode.
In the aftermath, the Expendables prepare to return home while Mauser and Booker depart from the team. Church reveals that he has now abandonned his job at the CIA and become a mercenary too. Ross and Maggie share a brief but passionate kiss before she also leaves, the Expendables get into their plane and fly home. On the way, the team propose a final toast to Tool.
Gerard Butler - Barney Ross
Tom Hardy – Jarrod Christmas
Donnie Yen – Ying Yang
Michael Jai White – Hale Caesar
Karl Urban – Toll Road
Danny Trejo – Tool
Morgan Freeman – Church
Kurt Russell – Trench Mauser
Bruce Campbell – Booker
Maggie Q – Maggie Chan
John Travolta – Claude Vilain
Gary Busey – Max Drummer
Cole Hauser - Hector