Rear Admiral John Quinn of the U.S. Navy's Bureau of Ordinance substitutes for Lynn Poole as host of this program about the Terrier surface-to-air missile developed by the Applied Physics Lab of Johns Hopkins University for the U.S. Navy. He asks a member of that Lab, Dr. Richard Kershner, to explain how the missile works and how it was developed. Dr. Kershner shows a film of the missile in action, noting that it doesn't actually hit the target but explodes within close proximity of it. On a mock-up he identifies the payload or warhead and the solid fuel rocket engine with booster rocket. The guidance control system allows "beam riding" as the onboard computer corrects the missile's course, and the missile's antennae pick up the intensity of the radar beams' mutations. A transmitter on the ground sends a reference signal to the receiver on the missile, a signature beam that prevents jamming by other radar beams. The electronic information received permits the four hydraulic tail fins to control its flight altitude. Dr. Kershner also explains a model of one of the terrier's control units. The first beam-rider missile was begun in 1947, and its problems were gradually eliminated, as shown in a film shot from a booster section showing "flutter." Development of such complex missiles requires not only a team of specialists in many fields but also systems engineers or specialty generalists to produce an integrated final product. A final film clip from 1952 shows target drones hit by Terrier missiles with warheads.