Flashman and the Mountain of Light takes place just after Flashman’s Lady, and it also falls between the two parts of Royal Flash, making it the fourth book chrono­log­i­cal­ly of the Flashman Papers and the ninth book published.

In the prologue, our hero finds himself telling Queen Victoria a much-edited version of how he came to acquire the Koh-i-Noor diamond on the crown’s behalf forty years earlier during the First Anglo-Sikh War. The actual story—at least according to Flashman and Fraser—is that Flashman, is sent from Madagascar to India, whence he is im­me­di­ate­ly sent to the Punjab. The in­de­pen­dent Sikhs are restless after a series of coups has left a seven-year-old boy as the Maharaja, with his mother Jeendan as Regent. Flashman is to be sent to the court at Lahore on a pretext, where he is to spy. Jeendan is notorious for debauchery and he promptly becomes intimate with her. War breaks out between the British and the Sikhs and Flashman gets caught in the middle.

Flashman is, by own his own frequent admission in the Flashman Papers, a poltroon, but here cir­cum­stances compel him to serve, and he acquits himself better than usual. He encounters such colorful characters as Alick Gardner (aka Gurdana Khan), a high-ranking American mercenary at the Punjabi court; Josiah Harlan, another American adventurer, who may have inspired Kipling’s “The Man Who Would Be King”; and the unorthodox General Sir Hugh Gough.