Hetty Wainthropp Investigates (1996)

S3E1 All Stitched Up

In a neighborhood gripped by fear from a teenage arsonist, the police find themselves powerless as terrified residents refuse to come forward. That's when Hetty steps in, disguising herself as the Irish sister-in-law of a local homeowner. Her mission is to blend in with the local sewing circle and gather intel on Lenny, the firestarter, and his crew.