The Blood Royal (Joe Sandilands Series #9)

The ninth mystery in the critically acclaimed Joe Sandilands series, a story of murder, mystery and espionage against the backdrop of the Romanov murders and the disappearance of the Tsar’s fortune.
 
It's 1922. Joe Sandilands is just back in England from his trip to India, and he has learned that his role at the Metropolitan Police has been expanded. Not only is he responsible for running CID, he is now also supposed to take up the reins on the Special Irish Branch, and he's juggling Irish terrorism and high-profile assassination attempts on prominent political officials. To top it all off, Joe locks horns with a Russian princess who is running a spy network out of Kensington. Then one of the assassination attempts is successful, and the pressure escalates. Joe must find out who is behind the violence: Irish or Russians?