Brother's Keeper

S4 E10: Samuel (Robert Knepper) learns just how powerful he can become and takes dangerous measures to reach his full potential. Meanwhile, as Tracy (Ali Larter) begins to lose control of her ability, one of her own comes in harm's way. Elsewhere, Sylar (Zachary Quinto) continues his battle with Matt (Greg Grunberg). Jack Coleman, Masi Oka, Hayden Panettiere, Adrian Pasdar, Sendhil Ramamurthy, Cristine Rose and Milo Ventimiglia also star. Kavi Ladnier, Jimmy Jean-Louis, Ravi Kapoor and Andrew Connolly guest star.