Captain America and Crossbones (2011 series) #1

On the island of Hazar in the Caspian Sea, a plague is causing people to mutate into monsters. A government agent visits Brock "Crossbones" Rumlow in prison to recruit him for a top secret black ops mission. [The story is interspersed with events from Rumlow’s early life: how he was a bullied kid who came under the protection of a Neo-Nazi gang, trained by the Taskmaster to be a killer, recruited by the Red Skull as his enforcer, finally assassinating Captain America.] He is dropped on the island where he finds a cache of equipment and the name of his quarry: Matvey Tarasov, a teenage boy. Locating the survivors in an abandoned nuclear plant, he claims to be a superhero from the Avengers and helps in arranging a defense. He also meets Matvey Tarasov, who is immune to the plague; as such he is feared and hated by the superstitious villagers. When the monsters attacks, Crossbones betrays his allies and heads to the chopper with the boy, allowing the monsters to invade the stronghold and slaughter the refugees. The agent reveals that the isolated island was deliberately infected to test the virus; they hadn’t counted on one citizen being immune. Learning they plan to dissect the kid to discover what is in his genes, Crossbones, feeling a bond with the abused boy, tosses the kid out the copter door to a quick and merciful death, shrugging off the agent’s threats of punishment.