The Four Men of the title are British WWI veterans who decide to work secretly against enemies of the country. They aren't above a bit of murder or sabotage to serve their ends, but they consider themselves to be true patriots.
Hugh Sinclair
Humphrey Mansfield
Griffith Jones
James Brodie
Francis L. Sullivan
Leon Poiccard
Frank Lawton
James Terry
Anna Lee
Ann Lodge
Alan Napier
Sir Hamar Ryman M.P.
Basil Sydney
Frank Snell
Lydia Sherwood
Myra Hastings
Edward Chapman
B.J. Burrell
Athole Stewart
Police Commissioner
George Merritt
Inspector Falmouth
Garry Marsh
Bill Grant
Hot
Girls' Night Out
Darkman
Hope
The Green Mile
Intime Conviction
Gumnaam: The Mystery
The Deadly Affair
Overdrive
Stowaway
Triage
The Commuter
Run
Operation Jackpotnalli C.I.D 999
Trauma
Robin
Trigger Point
All the Devils Are Here
The International
The Engineer