Three-Act Plot Analysis
Charlie returns to Paris and gets ready to do (verbal) battle with Marion for his daughter. He travels through Paris and sees it with new, sober eyes. He staves off Duncan and Lorraine.
Charlie tries to get to know his daughter again. He battles with his sister-in-law, Marion, and wins. He's still staving off Duncan and Lorraine, although it's clear that the duo wants to see him and relive the good old days.
Duncan and Lorraine show up at the Peters' home and ruin Charlie's plan; he returns to the Ritz bar to have his daily drink, and wonders how long he'll have to pay for the mistakes of his past.