- "Top-secret missions are always a risky business."
- — Tagline, from the front cover
When an ultra-secret project takes Fenton Hardy to Massachusetts, the Hardy Boys come home one afternoon to find that kidnappers have taken their mother. The kidnappers demand to talk to Frank and Joe's father within twenty-four hours -- or the boys may never talk to their mother again!
The key to the case is at Prometheus Computing, where Fenton is in charge of security. The company's latest product is a highly advanced computer chip sure to shape the future of artificial intelligence. But to protect the chip and their family, the Hardys will to rely on their natural intelligence and courage. They must find their father and infiltrate the DANGER ZONE before time runs out on their mother!
- Fenton Hardy
- Frank Hardy
- Joe Hardy
- Laura Hardy
- Aunt Gertrude
- Chet Morton (Casefiles)
- Biff Hooper (Casefiles)
- Phil Cohen
- Tony Prito (Casefiles)
- Con Riley (Casefiles)
- Larry Biester
- Captain Matyus
- Page 94 of the book contains an editing error when Tony says to Joe "Hey, give be a break.". It should be "Hey, give me a break."
- Page 13 establishes Bayport as being in New York State.
- Page 113 has Captain Matyus named Captain Martus at the bottom of it, even though near the top of the page the character is correctly called Matyus.