Here are some of his notable works:
Series:
* The Bulldog Drummond Series: Horler wrote numerous books featuring the dashing adventurer Bulldog Drummond, created by his friend and fellow writer, Sapper (Herbert Cyril McNeile). These books were immensely popular in the 1920s and 30s, and the character was also adapted for numerous films and radio shows.
* The Jim the Penman Series: This series follows the adventures of a master forger and thief, Jim the Penman, who gets involved in various criminal schemes.
* The Rex Van Ryn Series: These stories feature the resourceful detective Rex Van Ryn, who solves mysteries and battles against criminal organizations.
Other Works:
* The Mystery of the Missing Millions (1922): This early thriller features a stolen fortune and a race against time to recover it.
* The Man Who Was Thursday (1928): This novel, though not as famous as G.K. Chesterton's book of the same name, is a humorous mystery about a man who finds himself caught up in a conspiracy.
* The Black Abbot (1930): This is another early example of Horler's crime fiction, featuring a mysterious black abbot who is suspected of foul play.
* The Mystery of the Dancing Foot (1937): This thriller involves a series of murders and a baffling mystery.
* The Man Who Could Not Die (1946): This novel features a seemingly immortal man who becomes involved in espionage.
Horler also wrote a number of other novels, short stories, and plays, often with themes of adventure, suspense, and danger. His writing style was typically fast-paced, action-packed, and full of twists and turns.
While his work is not as widely read today as it was in the past, Sydney Horler remains a significant figure in the history of crime fiction. He helped to popularize the genre and his work continues to entertain readers who enjoy suspenseful tales of adventure and mystery.