Autumn 1910, secretary Carrie Grey witnesses a fatal tram crash. An avid fan of the tales of Sherlock Holmes, Carrie decides to investigate.
Then there are her new friends, William (her boss's son) and James (an engineer, a real ladies' man), both keen to help Carrie in her investigations.
And why was a photographer already at the scene, with his camera equipment set up and ready to take photographs of the incident?
Coincidence? Carrie thinks not.