Hong Kong remake of the European spy movie Passport to Hell: Secret Agent 3S3. A military plane carrying a nuclear load explodes mid-air after being hit by mysterious electronic rays. Secret agents are immediately ordered to trace its source. Sculptor Liang Tien Hong (Paul Chang Chung) returns to Hong Kong having been recalled by his uncle. He arrives to discover his uncle killed by agents. Liang’s uncle, inventor of the secret ray, dies after being tortured for information. The authorities believe the transmitter is still in Liang’s home. Steps are taken to find and destroy it for world peace.