Heartbeat (1992)

S4E2 Witch Hunt

Insp. Crossley has a hunch that an elderly woman might be behind a case of food poisoning. However, Kate uncovers the truth: the illness is actually caused by arsenic from aging wallpaper. Meanwhile, Nick informs Blaketon that the Inspector hasn’t been fully updating the CID, leading to Crossley’s removal from Ashfordly. The officers are taken aback when they learn that their new Inspector is a woman—Insp. Merchison!