 Angry over the defeat of a women s suffrage bill in Parliament, a zealous suffragette seeks out an anarchist, and acquires a bomb in the shape of a croquet ball. She does not intend to harm anyone, but the ball becomes exchanged with a real croquet ball. It is used in a game and explodes, killing a member of Parliament. Sherlock Holmes is convinced that someone else is responsible for making the switch, and he sets out to investigate.