Early in World War One, Gillies tries and fails to save the life of a British airman.
His father (a working-class Thames waterman) has his doubts, since this will mean Twigg postponing his hard-won scholarship to Oxford University, but they eventually agree.
He also introduces them to his friend Lord Ralph Dulwich, with whom he then goes to a party hosted by Sir John French.
In France, Twigg is involved in the organisation of the Battle of Loos, though his advice to bring the reserves closer to the front line is ignored by French despite its being backed by Douglas Haig.
This continues even when faced with Gillies' alter-ego Dr Scroggy - he goes around the wards dressed as a highland soldier to raise his patients' morale.