You are police officers in Cairo, Egypt in the early 1930s (the time of "Indiana Jones"). You are part of a special police unit called "Special Branch: Tomb Police", and it is your job to investigate crimes that involve archeology, ancient artifacts, museums, etc. In this world, some ancient artifacts have magic powers, and these are often evil, and must be hidden away from the general population (who doesn't know that magic exists at all).
Some of the police in your unit are "real" police officers, but others are civilians who help out the police by providing their unique skills and knowledge when needed. You are likely to find yourself working in a team with some police officers, but also an archeologist, a doctor, maybe a college professor, etc.
Actually, you are part of the "secret police" and report to the Mumar Zapt (the Chief of Secret Police), who in turn reports to the Chief of Police.
How Egypt is Run
Although technically an independent country at this time, Egypt is actually run by the British almost as a colony. Each important Egyptian government ministry is run by an Egyptian, who has a British "adviser".
The Cairo police department is an important government agency, and so has three police at the top: the Chief, Assistant Chief, and Chief of the Secret Police are all British. Almost all of the "rank and file" policemen are Egyptian, however. The "Special Branch" is mostly British although there are some people from other countries in it, and even a few Egyptians.....