It's Midsomer Barton's annual Oak Apple celebrations - and the body of tragic mother Marion Slade is found drowned in the stream by village children.
Amid the festivities, DCI Tom Barnaby and DC Ben Jones question villagers - grumpy riding stables owner Grace Starkey and her enthusiastic husband John, former travellers Mark and Helen Castle, and Marion's gardener Rob Pride. But when Barnaby spots Alistair Gooding and his mother Ursula on the rostrum he stops in his tracks. They look exactly like two people who were brutally murdered years before.
Marion's daughter Bella, died eight years ago at the age of 16 after contracting food poisoning. She was carnival queen and the competition has stopped ever since - until this year. Local GP Dr Wellow admits Marion was on anti-depressants but he never considered her a suicide risk.
Ursula chairs a meeting of the carnival committee at the Heart of Oak pub while John Starkey flirts with publican's wife Ruth Chalk. Meanwhile Starkey's wife Grace is being spanked with oak boughs by Dr Wellow.
A post mortem reveals that Marion had taken tranquilizers, causing her to hear voices - but marks on her arm suggest she might have been held underwater. Barnaby goes to her cottage - as does Ursula. She admits she's the sister of Iris Rainbird, a blackmailer who was killed at Badger's Drift, while Alistair is the spitting image of his creepy dead cousin Dennis.
As Ursula's daughter April tells Joyce about the tradition of gathering green oak boughs, a drunken Mark Castle struggles to fetch his own from the wood. He misses the village dog show - and is found later under an oak tree, his throat cut.
News of his death triggers a row between John and an increasingly despondent Grace Starkey, who's spent the afternoon in bed with Dr Wellow, while April furiously tells Ursula she wants to lead her own life. Traces of tranquilizer are found in Mark's body - could the same person have killed both victims?
Jones discovers Alistair has an interest in underage girls. Then a search of Bella's belongings reveals the true cause of her death. April takes to her bed in a catatonic state and another body is found. A new Oak Apple carnival queen is about to be crowned, but can Barnaby and Jones use clues from the past to find the killer?
ELIZABETH SPRIGGS THOUGHTS ON HER RETURN TO MIDSOMER
Elizabeth Spriggs loved becoming the first guest star to get a second appearance in the series.
"To come back to the show was marvellous because the first time around I just loved it. I remember feeling sorry when the first film finished - it was a pilot and they didn't know then if it was going to work. Little did we know!
"I think our return was sparked off by the Americans who kept asking whatever happened to the Rainbirds. They must have forgotten that we were murdered. So the producers Betty and Brian thought of the idea that I was the original character's sister.
"The script is wonderful, subtly contrived and it works perfectly. The crew was wonderful and it was like going home. I loved working with Richard Cant as my son again because he is such a darling man, so gentle and sweet natured. And John Nettles is patient and generous. He is so down to earth and makes everyone so welcome - that is one of the main reasons why it works. It's like a stage company."
Nine years after playing Iris, Elizabeth went through some slight costume changes to play Ursula.
"You will recognise her as the Rainbird sister - my nails are varnished but not bright red and I don't have to wear the dreadful teeth this time, I just have mine. Reg Samuel the costume designer is perfect and I always say he is half the performance. He gives me Camilla Parker Bowles hats in vivid colours and beautiful dresses and Ursula gets away with it.
"She really is nasty - an overbearing, bossy lady. Whether she means well or not I don't know, but she is vile. Sophie Thompson plays her daughter and she is like a little deer with big brown eyes. I just squash her all the time. It's like acting with a moth, she is so damaged. I felt terrible when I had to bully her!"
Like her character, Elizabeth lives in the country.
"I live in a similar cottage to Ursula, an Elizabethan cottage in the country. Filming the oak apple celebrations was just like the village fetes that I remember from years ago."
BACK TO EPISODE PAGE
MAIN EPISODE GUIDE