Hancock learns his secret - he is an Angel, and Mary (Ray's wife) was his wife. They've been alive for countless years, but when they are together they are weakened and become human. All other pairings have died, leaving Hancock and Mary as the only two survivors.
He was beaten badly 80 years ago, and when he woke he had lost all of his memory. Mary left to save them both and couldn't bring herself to tell him the truth.
Just as Hancock starts to get into the mood to gain something from his experience in prison, the Police Commissioner needs his help to take down a dangerous and armed crew that have hijacked a bank and taken hostages.
Using his new PR skills, Hancock carefully flies onto the scene, and thanks the police crews on the ground before walking casually through the line of fire to the rescue of a stranded officer. When he's asked to put an end to it, he takes out the bad guys one at a time - taking off the arm of the lead bank robber to stop him detonating a bomb. For once he is cheered by those around him and counted as a hero.
After being with Mary, Hancock stops by a store and stops a robbery - but is shot twice in the chest and rushed to hospital.
While he is in intensive care, the one handed bank robber plots his revenge in prison with Hancock's other victims. As Mary visits, bad guys show up and open fire - Mary is hit with a shotgun blast. A weakened Hancock is beaten to a pulp, but manages to throw the last of the bad guys out of the hospital window before he leaps far away, restoring life to Mary.
One month later, Mary is back at home with Ray and Ray's boy. Hancock calls in, in his new superhero outfit, and asks them to look at the sky -- where we see he has planted Ray's logo for a better world onto the moon.
After the credits -- Hancock is still doing his superhero thing, when a punk, who has taken a hostage, calls him by his favorite word. Hancock looks to the camera with a wry smile, but it cuts before we can see what happens next.