Nathan learns of his father's plans, while Flint and Knox launch attacks on Hiro, Ando, Peter, and Claire. Meanwhile, Matt tries to revive Angela, Sylar meets with Elle, and Mohinder begins testing of his newest superpower formula.

Hiro escapes Arthur but believes himself to be ten years old. Arthur sends Knox and Flint to capture Peter and Claire. Ando helps Hiro re-discover his powers. Nathan is shocked that his father is not only alive, but also leading a villianous charge to save the world. Syler learns to access his empathy and reconciles with Elle. Mohinder begins testing a new combination of the formula and discovers the need for a catalyst. Matt wakes Angela from her coma. Claire realizes that she is the catalyst.