Plot

A Marine Corps helo has a midair collision with an unknown aircraft; all but the pilot survive. Harm and Bud investigate. People from a mysterious agency take control of the site, and Harm locks horns with them, but he solves the mystery.

During an exercise a Marine Corps helicopter has a midair collision with an unknown aircraft above the Mojave Desert; all but the pilot survive. Harm and Bud investigate; Mac stays in Washington and plays games with Dalton and his colleagues. A mysterious alleged federal agency takes control of the crash site and runs away Harm and Bud. The other aircraft appears not to have crashed nearby; Harm and Bud learn more about it, and they run into trouble, but the Marines arrive and save the day. Harm figures out how the crash happened. Harm also meets Clark Palmer, whom he'll see again later. Mac makes an important announcement to the admiral.—DocRushing

Harm and Bud are sent to Twenty-nine Palms Marine Base to investigate the mid-air collision of 2 helicopters and subsequent crash of one helicopter which killed the pilot. Upon arrival at the crash site, they learn that the ""other"" aircraft was not another helicopter as was first thought. A piece of wreckage that is found that belongs to the ""other"" aircraft only deepens the mystery. When members of the Defense Security Division appear onscene with orders to take over the investigation and crash site, Harm becomes convinced that a major cover-up is in the works. The base commander, Col. Barrett gives Harm time to investigate further. When Harm and Bud are out driving the base at night, they see an unknown type aircraft flying above them and follows it, but are soon blocked by a fence over the road marking the property of the ""Bradenhurst Corporation"". Even though the signs indicated that ""Deadly Force has been authorized"", Harm crashes the gate to follow the aircraft.