"Allan and the Holy Flower" is a thrilling adventure novel by H. Rider Haggard, published in 1915. The story follows the British explorer Allan Quatermain, who receives a mysterious letter from his friend, Sir Henry Curtis, requesting his presence in Africa. Sir Henry has discovered a rare orchid known as the "holy flower," said to grant immortality to those who possess it. However, Sir Henry has also been kidnapped, and Allan must rescue him and retrieve the flower from the treacherous African interior.