"Mr. Grex of Monte Carlo" is an interesting play of intrigue between the Grand Duke Augustus Peter of Russia, whose incognito is Mr. Grex, an English Secret Service agent, Lord Huntersley and a young American millionaire on pleasure bent, Richard Lane. Mr. Grex and two other diplomats who unofficially represent France and Germany, plan to meet as if by chance in Monte Carlo for the purpose of arranging a secret pact.

Theodore Roberts
Mr. Grex, alias of Grand Duke Augustus Peter

Dorothy Davenport
Grand Duchess Feodora

Carlyle Blackwell
Richard Lane

James Neill
Herr Selingman

Horace B. Carpenter
Mons. Pitou

Frank Elliott
Lord Huntersley

John McDermott
Ernest
Robert Gray
David
Gertrude Kellar
Lady Wibourn

Lucien Littlefield
The Rag Picker

Theodore Roberts
Mr. Grex, alias of Grand Duke Augustus Peter

Dorothy Davenport
Grand Duchess Feodora

Carlyle Blackwell
Richard Lane

James Neill
Herr Selingman

Horace B. Carpenter
Mons. Pitou

Frank Elliott
Lord Huntersley

John McDermott
Ernest
Robert Gray
David
Gertrude Kellar
Lady Wibourn

Lucien Littlefield
The Rag Picker