When Nick Fury assembles the Avengers to take down a resurgent HYDRA, the team is shocked to discover their newest recruit is a fourteen-year-old former HYDRA experiment. Enhanced by a powerful Super Soldier Serum, trained in the brutal Red Room, and gifted with mysterious black flames that grow stronger when they sing, the young genius quickly proves they’re stronger than any Avenger expected. While Steve Rogers sees the effects of HYDRA’s experiments and Natasha recognizes the scars of Red Room training, no one fully understands the source of the black flames—or the teenager wielding them. As the Avengers fight to dismantle HYDRA once and for all, their newest member becomes key to an even more personal mission: rescuing Steve’s best friend, Bucky Barnes, the Winter Soldier. The problem? Before Bucky was HYDRA’s deadliest assassin, he was the one who trained them.