Nicky, the sister, killed Adam in self-defense after she learned from their son Ethan that Adam had been physically abusive toward Chloe, Nicky's sister and Adam's current wife. Nicky confronted Adam, who became violent, and she stabbed him with a pocket knife to protect herself and her family.
Additional context:
- Adam was married first to Nicky and had a son, Ethan, with her. Later, Adam married Chloe, Nicky's sister.
- Ethan was initially suspected of murdering Adam due to his DNA being found at the scene, but he was acquitted.
- Ethan witnessed Adam assaulting Chloe and contacted Nicky before the killing.
- Nicky revealed to Chloe that Adam had been abusive and that the stabbing was an act of protection.
- The show ends with Chloe and Nicky covering up the truth to avoid detection by the police.
