Alan King, co-owner of King's Crystal with his brother Charles, is killed in a car accident in Shanghai during a business trip with his brother Charles and accountant Peter Baxter. The company faces bankruptcy and the workforce, led by volatile glassblower Jack Tewson, is devastated.

Tensions are brewing throughout Midsomer Magna. Alan's son Ian shuns his mother Hilary to grieve with his close friend David Monroe; Sophie Baxter, daughter of Peter, is in love with Ian; and undertaker James Mason is in love with Sophie.

Six months later, the factory has closed and Charles weds his brother's widow Hilary. Ian is angry at the marriage and concerned by Tewson's claims that the company pension fund has been embezzled.

Peter fears an investigation into the accounts and puts his house up for sale. The next day he is found dead in the stream, with a stab wound to his chest. Meanwhile Cully is rehearsing for a production of Hamlet at the Midsomer open air theatre, refurbished thanks to Alan King's fundraising.

Barnaby discovers that an intruder broke into Peter's office the night he died and Tewson suggests the culprit could be Ian. Ian finds a sketchbook in his father's study.

The murder weapon is discovered - a Masonic dagger. Jones, a lapsed Mason, questions Charles, the Master of the Lodge, who reveals the dagger was Peter's.

Ian is behaving strangely - he makes amends with Charles, even becoming a Mason, then insults Sophie. He confides in David that he is close to the truth and David tells Barnaby he is worried for Ian's safety.

The next day, Ian is found dead, hanging from a noose similar to one used in his Masonic initiation, and Sophie is missing.

As Barnaby watches Cully in the performance of Hamlet he realises the play contains a message sent by Ian King before he died&ldots; But can he pick up the trail of clues to lead him to the killer?