Patriot Games

On holiday in London with his wife Cathy and their daughter Sally, former Marine and history professor Jack Ryan sees an ambush unfold in front of him and moves without thinking — breaking up an attempt to kidnap the Prince and Princess of Wales, killing one gunman and putting another, Sean Miller, in the dock.

The heroism makes him famous, and it marks him. Miller belongs to the Ulster Liberation Army, a splinter faction far colder than the movement it broke from, and once his comrades break him out of prison the ULA turns its attention across the Atlantic to Ryan's family. What began as a moment of reflex becomes a private war fought on his own doorstep in Maryland.

Clancy's 1987 novel is the earliest chapter of Jack Ryan's story, and the most domestic — no submarines, no fleets, just a man defending his household — and it is the book in which Ryan is drawn into the CIA for good.