A successful doctor who comes to Soldier Island because he is told that Ms. Owen is sick. He used to drink too much and once accidentally killed an old woman because he was drunk while operating on her. He is very preoccupied with maintaining his reputation, and hence his success. At the same time, he is a very gullible man. He trusts Wargrave and helps the judge fake his own death. Once the other surviving characters think that the judge is dead, Wargrave has free reign of the island. Wargrave eventually kills Armstrong by pushing him off a cliff.