Cadfael (1994)

S1E4 Monk's Hood

Title: Monk's Hood Plot: A wealthy estate owner decides to exclude his stepson from his inheritance, opting instead to bequeath his wealth to Shrewsbury Abbey. Soon after, he is discovered dead from poisoning. When Cadfael is summoned to unravel the mystery, he is taken aback to discover that the deceased's wife is his long-lost childhood love, whom he hasn't encountered in four decades.