Ghosts (S11E04)

Steve McAndrew's world is turned upside down when his teenage son, Stewie, is caught with drugs, prompting a reunion with his ex-wife, Tricia, as they join forces to pull their son back from the brink. Meanwhile, a troubled dementia patient breaks free from her nursing home, claiming to have witnessed a murder, leading the team to investigate the long-unresolved case of a policeman who vanished under suspicious circumstances in 1956, potentially a victim of foul play.