We look in on Charles Kane as he runs for governor of New York. We see him at the front of a huge rally. He rants about how he's the friend of the workingman and the underprivileged.
His wife Emily and his son are in one of the balconies. So yeah, it looks like Kane spent an evening with Susan Alexander while he was still married to Emily.
As Kane brings his speech to a triumphant close, a dude up in the balcony puts on his hat and leaves.
After the rally, Emily sends their son off in a car. Then Emily gets into a taxi and Kane wants to know where she's going. Emily has received some sort of anonymous message telling her to go to a certain address.
When the maid answers the door, she calls Mr. Kane by name. Kane and his wife Emily go upstairs and run into Susan Alexander, who says she was blackmailed to send the letter to Mrs. Kane.
Standing behind Susan is Jim Gettys, the man who's running against Kane for governor. Gettys wants Kane to withdraw from the governor's race or he'll publish the story about Kane's affair.
Emily says that Charles will withdraw from the governor's race immediately. But Charles refuses, even though he knows it'll destroy his family.
Gettys walks away calmly while Kane chases after him and screams at him.