Class lines are blurred when a baron's son is accused of killing his groom in this 1920s mystery.

The Nightingales are on a mission, set on solving a twenty year old murder to exonerate Lord Buxley. When the groom at a neighboring estate is bashed to death, the young heir becomes a suspect. Summoned by her fast friend, Lady Bess rushes to Castle Morse with Lady Vicky in tow, only to find herself knee deep in a baffling mystery.

Despite warnings from a certain handsome Detective Inspector, they begin investigating the crime. Apparently, the dead man was involved in a controversy that divided the village, giving several men a motive to murder him. Can they separate the red herrings from the real clues to find out the truth?

Meanwhile, a surprise guest arrives at Buxley Manor, throwing both upstairs and downstairs in turmoil.