When satellite-tracking stations around the world begin receiving radio signals from deep space, Joe Burke, owner of a small engineering company, is about to propose marriage to Sandy Lund, a woman he has known since high school. The signals consist of a repeated series of flute-like notes, which Joe recognizes. Joe plays for Sandy a tape recording he made a year earlier and it sounds just like the signal from space. Joe explains that he got the notes from a lucid dream that has come to him off and on since he was eleven. In the dream he is on a world with two moons and trees with ribbon-like leaves and he is holding a strange weapon, a kind of recoilless pistol. In his shop he makes a modified version of the weapon and when he tests it, it breaks loose from the workbench and slams into a wall hard enough to shatter the bricks.