High Citadel is a novel written by English author Desmond Bagley, and was first published in 1965.

In a fictional South American country, a small passenger plane is hijacked by its co-pilot, a Communist agent, and crash-lands at an airstrip high in the Andes mountains.

But due to a collapsed bridge, the Communists aren't there to meet the plane, and the co-pilot is killed in the landing.

O'Hara and the passengers hold off the Communists, using improvised weapons suggested by the historian and constructed by the scientist from the scrap of an abandoned mine.

The siege of the 'high citadel' becomes increasingly dangerous as Communist reinforcements arrive, while the mountain-crossers encounter extreme hazards and political treachery.