On Christmas Eve, Dr. Levine comes to a Mott Street tenement to see his elderly patient, Abraham Goldman. Abraham is unimpressed by the young doctor's warnings about his health and talks about his brother Sam, who owns a cabbage field in California and will be sending him the money he owes at any time. Levine focuses on Abraham's health and says that regardless of money, he needs to go to the hospital. Abraham refuses to leave, insisting that his nine-year-old grandson Mikey needs him. The boy's parents are dead and Abraham is the only thing that he has for a family. Levine speaks of the Angel of Death, saying that he's right outside, and asks what he should tell him. Abraham dares the Angel of Death to come in so he can spit in his eye, and insists that the Messiah will come.
Dr. Levine leaves and runs into Miss Moretti, with the Bureau of Public Assurance. She says that they've heard reports that Mikey's homelife is unsuitable and she's there to investigate. Levine explains what has happened and that Abraham expects to receive money from his brother. Miss Moretti warns the doctor that Sam is a senile patient in a California convalescent home and doesn't have a penny to his name. Levine warns her that Abraham will fight her tooth and nail to keep her from taking Mikey, the one thing he has left in his life, and she reluctantly agrees to wait until after Christmas to separate grandfather and grandson.
Mikey makes tomato soup for Abraham, who describes the Messiah as a big black figure looming in the sky who will bring gifts for everyone. The boy is enraptured, and Abraham asks him to bring the food back later. As Mikey leaves, a dark shadows falls across Abraham's bed. Realizing who it is, he yells defiance at the Angel of Death, refusing its promises of peace. Abraham says that peace isn't worth the price of losing his grandson. Mikey runs in at the noise as the shadow disappears, and Abraham lies, saying that it was the Messiah and that he promised he'd be there later with gifts. Mikey says that the only thing he wants from the Messiah is Abraham, alive and well.
Once Abraham dozes off, Mikey goes out into the streets to find the Messiah and brings him back. He runs into a street-corner Santa, who wonders why the boy is out at night. Mikey, a Jew, has no idea who Santa Claus is, and the Santa tells him that he won't find the Messiah in the poor part of the city. The boy keeps going and finds a religious fanatic predicting the end of the world. The man freely admits that he's the messiah, and says that all will die as is prophesized. He tells Mikey to prepare for his grandfather's death and grabs the boy, but a large black man grabs the man and sends him on his way. Mikey assumes that the big black figure is the Messiah and asks him to come and heal his grandfather. The man, Buckner, appears more bemused than anything and follows the boy back to the tenement. They arrive and discover a police car and a crowd outside. Abraham has fallen ill and Levine has been called to the scene. He tells the police that Abraham is too ill to be moved.
Mikey and Buckner go upstairs and the boy explains to Levine that he has found the "Messiah." Levine sends the boy to bed and then checks on Abraham. The old man has recovered consciousness, and the doctor explains that he came back to check on him and found him unconscious. He offers to bring Mikey in, but Abraham tells the doctor that the Angel of Death visited him again and said that he'd be back for a third and final time at midnight to take Abraham away.
A weary Levine goes out into the living room and talks to Buckner, explaining that Abraham needs a miracle at this point. Buckner asks if he believes in miracles, and Levine admits that scientifically he doesn't… but as a practicing Jew, he accepts the idea of the Messiah, and the Angel of Death, and miracles. Mikey, dressed for bed, comes out and assures Levine that everything will be fine. The doctor tells him to kiss his grandfather goodnight and not wake him. As Buckner and Levine watch, a wind blows through the apartment. Levine dismisses it as a coincidence, but Buckner notes that Abraham is waiting for someone to arrive. Mikey comes out, worried about his grandfather, and asks Buckner to heal him. Levine tries to tell him the truth, and prepare the boy for Abraham's death, and the wind blows up again. The doors blow open and Mikey runs into Abraham's room. There is a shadow looming over the old man. Levine starts to go in after the boy, but Buckner draws him back and says to let them have a moment alone.
Mikey steps out seconds later and asks Levine to check on Abraham. The doctor is surprised to see that Abraham is not only alive, but clearly in much better condition. The old man says that he had a dream of Mikey and Levine and someone else outside his room. However, none of them remember Buckner. The bells ring outside, announcing that it is past midnight, and the Angel of Death hasn't taken Abraham after all. Abraham offers to pay Levine, but admits that he's been deluding himself all these years and that Sam will never send the money he owes. There's a knock on the door and Mikey signs for a special delivery envelope. He looks up at the postman, who is Buckner, but doesn't recognize him. The boy takes the envelope to his Abraham, who opens it and finds a check for $10,000 from his brother Sam.
Levine leaves the tenement for home, and runs into Buckner outside. Levine thanks him for the delivery, and assures him that it pleased. Buckner smiles and notes that sometimes God remembers the tenements, and wishes Levine a happy holidays before walking away.