Who?

A man crouches on a porch at night, extending his hand toward a dog wearing a blue light on its head, which then runs down a dark alley. The scene cuts to a couple in a car, the man driving and the woman in the passenger seat, as the car drives down a residential street at night. The dog, now seen from behind, runs down the alley with the blue light flashing. The sequence ends with a low-angle shot of a white picket fence at night.