Feeling nostalgic for the fun times he spent with his deceased father as a child, Charlie Miller purchases a quartz radio kit from a toy store in an effort to similarly bond with his son Kenny. Despite Charlie’s insistence that it’ll be fun, Kenny shows little interest in the kit. Somewhat crestfallen, Charlie confides in his wife Janet that he’s upset that Kenny never even knew his grandfather, who passed away in World War II. Rather than return the kit to the store, Charlie decides to relive a little of his youth and builds the quartz radio himself. He is shocked when it not only works, but when it also begins to pick up a faint transmission in what appears to be German. Over a period of several days, Charlie is able to translate the transmission. It’s a communication between Berlin and a German U-Boat at sea, which is searching for an Allied naval convoy. Charlie knows all too well the result of this transmission, as on one of the ships destroyed in 1942 was his own father. Charlie formulates a plan that will prevent his father from dying back in 1942, and thereby giving Kenny a chance to meet the grandfather he never knew. Charlie comes home the following evening with a similar package from the toy store. It is a quartz-transmitter kit. He assembles the kit and sends a message of his own, after consulting World War II history books on the particular war campaign. He sends a transmission to the U-Boat changing the coordinates of the Allied fleet.
When nothing immediately happens around him, Charlie gives up sending the transmission and turns in for the evening. Charlie is awoken the following morning by his own father! He keep telling Charlie that he needs to get up, and that they need to open the butcher shop. There are deliveries and pick-ups to be made. In a haze, Charlie can’t tell whether he’s dreaming or not.
But his father is clearly alive and well. When questioned about the whereabouts of Janet and Kenny, Charlie’s father has no idea who he’s talking about. As Charlie stumbles towards the door, his father stops him, reminding Charlie to put on his ID badge on his butcher’s apron. The door to the butcher shop opens and Charlie’s father address the customer in fluent German. The customer is a SS Officer. Charlie stumbles past the Gestapo officer into the street of small town America. There are more SS officers walking down the sidewalks, and Swastika flags hang from street lamps and nearby buildings. In his attempt to change the past, Charlie has also altered the end result of World War II. Charlie is now trapped in a world in which the Germans won.