[2] As a young man, he worked as a reporter and columnist for the Syracuse Herald newspaper until the late 1890s, when he published his first novel, a romance titled Arms and the Woman.

[citation needed] MacGrath (as he spelled his name then) continued to write novels for the mass market about love, adventure, mystery, spies, and the like at an average rate of more than one a year.

The Douglas Fairbanks Production Company made a feature-length adventure film, The Mollycoddle (1920), based on MacGrath's short story of the same title.

Directed by Victor Fleming, the film featured Douglas Fairbanks, Ruth Renick, and Wallace Beery; it was distributed by the newly created company United Artists.

The young Boris Karloff, who had a few uncredited movie roles, was said to have chosen that stage name in 1920 for his first screen credit from MacGrath's novel The Drums of Jeopardy.

Published by The Saturday Evening Post in January 1920, it had featured a Russian mad scientist character named Boris Karlov.

In "The Short Autobiography of a Deaf Man", an essay published in The Saturday Evening Post (23 April 1932), MacGrath wrote about having struggled early in life as a result of a hearing impairment.

At a time when deaf people were often considered as lacking intellectual acuity because of difficulty in communications, MacGrath had concealed this condition from his employer and others.