Sarah Walker

Sarah Walker walks into a Buy More as "Sarah Heartfelt," a new saleswoman using an assumed name and an easy smile. In reality she's a CIA agent assigned to protect Chuck Bartowski after government secrets end up lodged in his brain. Poised and highly trained, she's supposed to keep him at arm's length.

The show's trick is making a stone-cold professional visibly struggle to stay that way, and Yvonne Strahovski plays the fraying edges beautifully — the flicker of warmth she can't fully suppress under the spy poise. Sarah is competent enough to anchor the action, but it's her restraint, and its cracks, that make her compelling.