The following detailed plot synopsis appeared in the December 6, 1919 issue of The Moving Picture World:

Harvey Hanford, the part played by Houdini in The Grim Game, is a special writer on The Call, who is noted for his nerve and daring in gathering news.  He has an eccentric millionaire uncle who lives with his ward, Mary, and will not let Harvey come near him.  The old man knows that his nephew and his ward are in love with each other, and is opposed to the match.  He is also aware that he is surrounded by three men, any one of whom would profit by his death.  The first is his lawyer, Richard Raver, who has misappropriated some the Cameron funds.  The second is Dr. Tyson, his physician, who expects to marry Mary, heiress to the Cameron millions, when their owner dies.  Clifton Allison, owner and publisher of The Call, is heavily in debt to Cameron, and the old man has threatened several times to drive him to the wall. 

A plan is hit upon by Harvey to work up a big sensation for the paper by getting the old man away secretly and then making it look as if he (Harvey) had murdered his uncle.  After he has been convicted of the crime, Dudley Cameron will be brought back and circumstantial evidence will be given a heavy blow.  The three men agree to this, but each one is determined that the old millionaire shall never return home alive.

The scheme is set in motion and Harvey is arrested for the murder of his uncle.  Then commences a series of Houdini escapes, the last one being a genuine thrill and the most dangerous of the Handcuff King’s career.

While trying to change in midair from one flying machine to another, the two airplanes crash into each other.  This, of course, is an accident, but the camera caught it and also the dive to earth of the machines which followed.  None of the actors in the accident were seriously hurt, and The Grim Game is able to show on the screen an “escape” that is a thriller of thrillers.  The story is brought to a highly satisfactory close, and Harvey and Mary are united.