Bruce Murdoch is an agent with the British Intelligence.
He is considered by most the people who know him to be an earnest but still "young" man though he is 28 years old when the six-adventure series begins, hardly really young. Perhaps it is because, based on the scanty information provided, he apparently has done nothing really before he is offered a chance to perform a useful role in society by becoming an operative.
Idle is a good word for his lifestyle prior to his new career. He is obviously well-off because he has no, and apparently never has had, employment and yet he lives very nicely and comfortably and even has his own batsman, an irascible fellow known as Briggs who was in the vicinity needing a job when a 21-year old Murdoch had a few too many and got into a tight spot. They have been friends and companions ever since.
It is not disclosed what prompted Murdoch, living the easy life, to get serious and make a difference but he did and he is to be commended for that. When he is approached by Sir Robert Holt and offered a 5-year contract to act as a secret agent, he quickly agreed. Apparently he did not mention this to Briggs but somehow soon thereafter, Briggs comes on board as well.
A brief note about Holt is warranted. He is a fairly short, quite rotund individual who is bald and has a pinkish tint to his complexion all over his hairless head. This is of interest since because of it he is affectionately referred to by his agents as the "Pick 'Un". I mean, a lot. It is almost a password. And he does not seem to mind.
One enjoyable aspect to Murdoch's new vocation is his newness. He is definitely smart and quick-witted and eager to succeed but he is also just starting at this and he does make a few mistakes, a couple which nearly kill him. Luckily his innate skills help out as does Briggs and a few other agents.
That includes the lovely and far more experienced Mary Dell. Unlike Murdoch, she is not new to the business and she has skills that continue to impress and delight Murdoch as they become enchanted with each other and soon become an item. Murdoch is an obvious fan of adventure but he pales compared to Dell who has little qualms about, well, anything. She is also quite brilliant and has an invention or two under a pseudonym. How and why she became an agent remains unknown but she is one of the Service's best.
A good agent needs a good nemesis and Murdoch and Dell would acquire one halfway through the series when they come up against the "Withered Man", a foe who would be their target for two cases and then their stalker for one. An interesting foe is the Withered Man.