PBS | 9:00 pm
There’s a changing of the clerical guard in the offing during Season 4, which opens with a two-hour premiere set in 1956. Sidney (James Norton) is itching to shake up his life a little, but he gets that and more with the arrival in Grantchester of the Rev. Nathaniel Todd (guest star Paterson Joseph), an American minister, and his civil rights activist daughter, Violet (Simona Brown). A murder causes simmering racial tensions to spike, while elsewhere, Geordie (Robson Green) investigates a decaying slum that’s a hotbed of vice.