When the cargo ship Teresa del Mar anchors at the Latin American island of Providencia, boatswain Víctor (Hugo Stiglitz) disembarks for a break and meets Beni (José Sacristán), a local beggar. Soon after, Víctor is mugged and left stranded. Having lost his ship, he accepts Beni's invitation to stay at a shelter housing local vagrants. Víctor quickly uncovers a grim exploit running under the island's authoritarian regime: the impoverished residents survive by routinely selling their blood to the "Plasma Company"—a lucrative enterprise run by Lucas Almeida (Jorge Luke), the son of the island's dictator. As Víctor witnesses the corrupt scheme draining the islanders, he joins forces with Beni and local woman María (Isela Vega) to fight against the predatory regime harvesting the people's blood for profit.