She is a friend of Phryne's. Dr. Macmillan and Phryne reunited during Phryne's voyage by ship from England to Australia in Cocaine Blues. Dr. Macmillan is described as being of around forty-five years of age, with a broad, strong physique, rough and calloused hands, and a weatherbeaten complexion.[3] Her black hair, now turning white, is cut into a 'short Eton crop' and she tends to dress in men's clothes for convenience.[3] Phryne and Dr. Macmillan first meet when there is a 'flu epidemic at a remote island, and Phyrne steps in to fly Dr. Macmillan in on a plane despite dangerous weather conditions. She then assists Dr. Macmillan in attending to the unwell residents of the island, including slaughtering a Highland cow to make them broth.[3]