The Godfather ending explained

What happens

Michael becomes godfather to his sister's child while his men murder the other families' heads and Carlo, who betrayed Sonny. He then lies to Kay about Carlo. The door closes on her, and the men greet him as Don Corleone.

The last image

Kay stands outside the room, looking in, as the door closes on Michael, now addressed as Don Corleone.

What it says

Michael began as the family's outsider and ends as its master. The baptism joins his vow and his killings, and the shut door shows what it cost: Kay, and the honest life he once wanted, are left outside.