Years pass, and she brings up their young son, also named Gregory, and ensures that he is taught several native languages.
When she dies, Gregory is left alone in the world, with a small bank account and a mysterious tin box only to be opened when he is certain of his father's death.
Gregory obtains a position as interpreter in the expedition under Lord Kitchener which is advancing into the Soudan to attack the Dervish forces.
He endures many hardships and dangers in the great campaign, and gains high distinction, while continuing his search for his father.
A common theme, shared by this book, is the threat to the Empire from a less civilised foe; in this case the self-proclaimed Mahdi, the prophesied redeemer of the Islamic world, and his followers, who had already inflicted severe defeats on British forces.
This is mainly training for physical strength, by playing games and receiving fencing lessons, but also includes ensuring that his "manners were those of an Englishman", such as chivalry, wit, compassion and charity.
[1] As was common at the time of writing, Henty stereotypes the races in the story along martial lines, with the English as a physical and moral benchmark.
Henty qualifies this praise, however, by infantilising the Sudanese and making clear that they require English leadership and discipline to be most effective.