This photo (Still 298-25) is one of 5 photos that appeared in a 1920 Cinema Chat Ad for The Grim Game.

So who are the characters/actors depicted in this photo?

Harvey Hanford (Harry Houdini), Dr. Harvey Tyson (Arthur Hoyt), Ethel Delmead (Mae Busch).

So what is going on in this photo?

Dr. Tyson, Ethel and Hanford stop a second to discuss final arrangements of Hanford’s scheme then Dr. Tyson and Ethel start toward the gate.
[Scene 123 paraphrased from Paramount Script]

According to the details of Hanford’s scheme, Dr. Tyson is to order Cameron to the mountains for his health.  He is to arrange for the old man to go at night, secretly, accompanied by Ethel Delmead, a cabaret singer – selected for her beauty and winning personality – who will be coached in her part as nurse.  [The Grim Game Cast and Story]