From the text:
What is the game about?
It's 1886. There’s a new democrat in the White House, and he needs protection - protection from his own sister.
What do the characters do?
The characters are United States Secret Service agents, tasked with keeping the intelligent, inquisitive, and utterly devious Rose Elizabeth Cleveland from discovering any of her brother’s secrets. He has a whole lot of secrets.
What do the players do?
Grover Cleveland is a three-player game. The players rotate the responsibility of playing their own version of Rose, scene by scene. In each scene, one player is Rose, one is an Agent of the Secret Service, and the third is “the World” - everybody else, and an adjudicator. The Rose player portrays her from the point of view of another player’s Agent character - to that particular Agent, perhaps she is a cruel beast, or a bizarre free-thinker. The Rose player pushes hard to discover Grover Cleveland’s dirty linen, and the Agent player pushes back.