Barney Ross leads his team of seasoned mercenaries, known as The Expendables, on a covert mission to intercept an arms deal aboard a moving train. During the operation, they discover that the arms dealer they are targetting is Conrad Stonebanks, once a co-founder of The Expendables, who has become a ruthless weapons trafficker. After a fierce conflict, Stonebanks escapes, vowing revenge. Feeling haunted by this encounter and the risks posed to his old team, Ross decides it is time to bring in new blood. He disbands his current lineup and, with the help of scout Bonaparte, recruits a younger, tech-savvy new team members to hunt down Stonebanks.

The new recruits, each with unique skills, inject vitality into the mission. However, when they attempt to capture Stonebanks in Somaliland, things go awry. The experienced yet now sidelined original team members question Ross's decision to bench them, leading to tensions within the group as they grapple with their roles and relevancy in a changing world. The mission to take down Stonebanks thus becomes not only a battle against a formidable adversary but a test of unity and adaptability for the once-unshakeable brotherhood of mercenaries.