Resuming a “Then” section, Casey confronts Boone about why he called Katherine, and Boone confesses to her that she doesn’t know the full extent of his and Katherine’s relationship. Earlier that summer, when the Royces were at the lake house for Labor Day, Boone and Katherine had flirted with one another, swimming together at night. Before Katherine left for New York, the flirtation culminated in a kiss. The morning that Casey saved Katherine from drowning, she’d swum over to see Boone and told him he needed to stop calling her, effectively ending their relationship. Later that night, Katherine called Boone and left him a voicemail, which he ignored and deleted. Casey realizes that this must have been the phone call she witnessed that night when spying on the Royces.

However, Boone’s lie creates doubts around everything he has said. Casey asks if he gave Katherine anything to drink that last morning when they were together, and when he answers lemonade, Casey wonders if it was Boone who poisoned Katherine. Feeling unsafe, she grabs a knife and demands he leave and never return to her house again.

Downing several drinks beforehand, Casey sets about locking up her house, which forces her down to the basement she’s been avoiding.