Frank and Joe's friend Phil Cohen, Bayport High's resident electronics whiz, has landed a job at Futron, a manufacturer of highly classified, high-tech military equipment. But the work is loaded with occupational hazards. The Hardys learn just how hazardous when both Phil andhis boss disappear...leaving only a trail of blood behind.

The enormous significance of the case becomes clear when the boys come face-to-face with the Gray Man, a top operative for the ultrasecret Network. The investigation leads Frank and Joe from kidnapping to murder...and ultimately to distant, dangerous shores, where a massive threat to global security is waiting to explode.