During their first night aboard, Ruby's (Merritt Wever) mind is consumed by sex, while Billy (Domhnall Gleeson) probes for personal details she's reluctant to give up. Comforted by the fact that her husband believes she's on a weeklong yoga retreat – and determined to make Billy jealous – Ruby brazenly connects with Derek (Saamer Usmani), a stranger on the train. Meanwhile, Billy works to shake a persistent figure from his past. 

Written by Adam Countee; directed by Kate Dennis.