影片开场，巴尼·罗斯（西尔维斯特·史泰龙 Sylvester Stallone 饰）带领敢死队的老伙计李（杰森·斯坦森 Jason Statham 饰）、贡纳（杜夫·龙格尔 Dolph Lundgren 饰）等人驾驶直升机劫持火车，救出了被囚禁的用刀高手医生（韦斯利·斯奈普斯 Wesley Snipes 饰）。经过短暂的休整，他们奔赴索马里潜入某倒卖军火组织的老巢中执行任务，谁知巴尼发现该组织老大竟然是当年本该死去的敢死队战友康拉德·斯通班克（梅尔·吉布森 Mel Gibson 饰）。一番激烈的交火过后，斯通班克成功逃脱，而敢死队方面则损失惨重。 　　此役过后，不仅军方和敢死队藏着一股怒火，连斯通班克也被彻底激怒，最强的硬汉迎来生死对决……Barney (Stallone), Christmas (Statham) and the rest of the team comes face-to-face with Conrad Stonebanks (Gibson), who years ago co-founded The Expendables with Barney. Stonebanks subsequently became a ruthless arms trader and someone who Barney was forced to kill... or so he thought. Stonebanks, who eluded death once before, now is making it his mission to end The Expendables -- but Barney has other plans. Barney decides that he has to fight old blood with new blood, and brings in a new era of Expendables team members, recruiting individuals who are younger, faster and more tech-savvy. The latest mission becomes a clash of classic old-school style versus high-tech expertise in the Expendables' most personal battle yet.