Carter is summoned to a meeting of the Joint Intelligence Chiefs at CIA headquarters. Carter learns that Fan Su – an anti-communist agent he helped on an earlier mission (described in Dragon Flame) has requested his help in supporting an anti-communist underground movement within China. Fan Su is currently in San Francisco. Carter also learns that Chinese forces are constructing a 500-mile long tunnel beneath the Chumbi Valley from Tibet into India to invade India and to conceal construction of the world's largest hydrogen bomb. Carter's mission is to enter China and destroy the bomb and tunnel before they can be used.