Lew Marsh Don Ameche is a pharmacist in the small town of Hartfield, Iowa. When he receives the news that his only son, Rusty, has been killed in the war, his grief overwhelms him and he withdraws from life.
One day, the spirit of his dead grandfather, known as Gramp Harry Carey, visits. He is upset by Lew's prolonged mourning and the isolating effects it has on the family. He tries to send him away, but Gramp has "all the time in the world." With those words, Gramp guides Lew on a spectral walk through the town and back through memories, showing him key moments from his life and Rusty's.
The tour begins with Lew and many Hartfield residents returning home after their service in World War I. Lew learns that his former girlfriend Velma has married a Marine just after the war; briefly afterward he meets Agnes, they fall in love, and they marry Frances Dee. Gramp's health falters but he endures, living long enough to see the birth of Rusty, Lew and Agnes's son, who proves to be a lively, independent boy who cares for his friends and becomes a devoted member of the Boy Scouts.
As Rusty grows, he experiences the small-town rhythms of life: helping at the family pharmacy, showing kindness to those in need, and even taking the risk of giving medicine to an old man who cannot pay, and tucking away some of his own savings in the cash register for a future treat. The memory then shifts to his teenage years, when he falls in love for the first time at eighteen with Gretchen Barry Cara Williams. Gretchen soon ends that romance for a younger man, a development that Lew and Agnes both anticipated, and the heartbreak is softened by Lew's quiet consolation.
Toward the edges of the border between memory and present, Lenore Prentiss Ann Rutherford emerges as a more mature figure—the once childhood friend who has grown into a striking woman—and Rusty notices her growing interest.
The flashbacks then sweep forward to the grim years when the Nazi ascent in Germany and the invasion of Poland intrude on the world. Some of Rusty's friends join the Canadian armed forces, but Rusty remains in Hartfield to help in the pharmacy. He later leaves to study for his pharmacy certificate, and eventually joins the Navy, bidding farewell to his parents and to Lenore.
Back in the present, Gramp insists that Rusty lived a wonderfully full life, a life he believes was complete even though it ended too soon. Lew struggles to accept this, and Gramp presses him to return to normal life, including a trip to the town pharmacy that evening. There, Lew encounters a young sailor named Tony Cavrek Harry Morgan, a survivor who agreed to tell Rusty’s parents what happened if Rusty ever died in action.
Tony shares the last hours of Rusty's life: the ship is struck by torpedoes, and Rusty, carrying a wounded man to safety, endures a second hit that sends Tony into the sea. The brutal toll of war is laid bare in that moment, and though Tony's account confirms a heroic, selfless end, it also deepens Lew's sense of loss. The film closes on the restrained, aching memory of a family bound by love, memory, and the quiet courage Rusty showed in his final hours.
