YMMV / Midsomer Murders S 7 E 6

• Complete Monster: Agnes Waterhouse is a sociopath obsessed with the "perfect death" with a liking for burning her victims alive. To eliminate potential obstacles, Agnes traps the local consulate in a straw woman to have him burned alive, then murders the consulate's gay lover; attempts to take the life of a doctor by setting his clothes alight with phosphorous; and murders the innocent schoolteacher Liz Francis by bludgeoning her with a candlestick and setting her alight. Agnes tosses the blame on her rival and nearly commits Murder-Suicide with her ward Alan Clifford. When asked why she murdered Liz by a grieving Dan Scott, Agnes's only response is a cheerful smile and a remorseless affirmation of "I had to".