High School student David Lightman has a talent for hacking. But while trying to hack into a computer system to play unreleased video games, he unwittingly taps into the Defense Department's war computer and initiates a confrontation of global proportions. Together with his girlfriend and a wizardly computer genius, David must race against time to outwit his opponent and prevent a nuclear Armageddon.

Aging Major Palgrave, an idiosyncratic but charming mystery writer, reveals to Miss Jane Marple that one of the guests at a luxurious Caribbean resort they're staying at is a Bluebeard-type wife murderer. Unfortunately, the Major succumbs to an apparently accidental overdose of alcohol and blood pressure medication before revealing the killer's identity. When it's discovered that the medicine belonged to another guest and the revealing photograph the Major was carrying is missing, Miss Marple realizes that the serial killer has struck again and more murders will follow.

Mycroft Holmes hands Sherlock Holmes the case of the Master Blackmailer.