Henry Ransom was an author, and the American friend of Dr Merrivale Carr.
Ransom wrote up the cases Dr Carr sold in best-selling novels, making Dr Carr internationally famous.
In 1920, Ransom was present at Lord Farthingale's country retreat, when Dr Carr gathered everyone in the library to reveal who killed Sebastian Marten and Paul Steiffers. Carr believed the murderer was Kitty Kickshaw, who had taken the identity of society hostess Glenda Neil. Immediately after Dr Carr declared this, the Ninth Doctor and Rose entered, explaining that the deaths were in fact a result of "invisible aliens". Dr Carr protested against this. Ransom claimed that Dr Carr could make "a quick study of any stranger". When the Doctor challenged Dr Carr on this, he failed to do this.
A haze appeared, accompanied by a buzzing sound. Bart Faversham had started being lifted up and was tossed into the fire. The Doctor and Rose figured out that it was the drive of the invisible aliens' spaceship inadvertently causing this. The Doctor signalled the ship with standard galactic code of the 455th century to repair the ship.
When the haze subsided, Dr Carr investigated the police box Janet Farthingale discovered in her room. While he assumed that he would never see the Doctor and Rose again, they proved him wrong, and revealed that the blue box was their spaceship, in which they departed. When Dr Carr asked Ransom to write up the case, Janet told him, "Not on our honeymoon, he won't be." (PROSE: Doctor vs Doctor)