Tom Horn (November 21, 1860 - November 20, 1903) was an American Old West lawman, scout, soldier, hired gunman, detective, outlaw and assassin during his lifetime. On the day before his 43rd birthday, he was hanged in Cheyenne, Wyoming for a murder he probably did not commit.

Although Horn's exploits as an assassin far overshadowed any other accomplishments he made during his lifetime, during his time as a Pinkerton Detective he killed seventeen men in regular shootouts during his four years of employment with them, between the years of 1890 and 1894. This was many times more that of men who would go on to be more famous and well known as lawman/gunfighters, including Wyatt Earp, Pat Garrett, Doc Holliday, or Bat Masterson. Of the Old West gunmen, with known confirmation of their shootout exploits, only Bill Hickok, John Wesley Hardin and James "Killer" Miller would be close to that number.

A renowned former army scout is hired by ranchers to hunt down rustlers but finds himself on trial for the murder of a boy when he carries out his job too well. Tom Horn finds that the simple skills he knows are of no help in dealing with the ambitions of ranchers and corrupt officials as progress marches over him and the old west. Written by Keith Loh