The Crimson Feather (S05E08)

Mrs. McCarthy is delighted to have her daughter Joselyn visit but Father Brown suspects there's something untoward about her unscheduled appearance. Meanwhile at The Crimson Feather club, manager Maurice lends some money to one of his dancers, Verity. She's going to be a very busy girl paying it off... The next morning Mrs. McCarthy finds that Joselyn has disappeared - only a note and long red feather remain. Bunty examines the feather and says that one place springs to mind... Bunty infiltrates the club and is employed as a dancer, spotting Joselyn inside. (iTunes)