Endeavour Muse explained as ITV's Inspector Morse prequel explores one of its most intense and heart-wrenching cases yet

Endeavour Muse is the opening episode of series 5 and it's one of the most heartbreaking and intense of them all

Endeavour Muse explained. Seen here are Endeavour Morse and Fred Thursday in Endeavour
(Image credit: ITV/BritBox)

Endeavour Muse is the opening episode of the ITV drama’s fifth season and it’s airing again, five months after the show ended. 

Endeavour season 9 rounded off the long-running ITV drama in emotional style as fans had to come to terms with Endeavour’s end. Inspired by Colin Dexter’s books, it is a prequel to Inspector Morse and focuses on Endeavour Morse as he started out in his career with the show-only character DCI Fred Thursday guiding him. Whilst we might not see any new episodes featuring the dynamic duo, all is not lost as ITV3 is currently re-showing older episodes. 

The next to be broadcast is Endeavour Muse, episode 1 of season 5, which airs on 14th August at 8pm-10pm and originally premiered in 2018. This is an especially devastating episode and here we explain Endeavour Muse, including who the killer is, what happened to the Fabergé egg and why Joan is back...

Warning: This article contains references to sexual violence and suicide which some might find upsetting. This article also contains spoilers for Endeavour Muse.

SHAUN EVANS as Endeavour and ROGER ALLAM as DI Fred Thursday.


Endeavour Muse ending explained: Who killed Sikes, Grey and Lake? 

Just like Vera The Sea Glass, the Annika ending and the rest of the ITV drama’s episodes, the Endeavour Muse episode had a self-contained storyline - and arguably one of the most emotional episodes of all. It was certainly a heart-wrenching episode to kick off season 5 and saw DS Endeavour Morse, DCI Fred Thursday and the team investigating three particularly gruesome deaths. Endeavour Muse’s first case was the murder of Joey Sikes, an associate of gangster Eddie Nero who was found shot multiple times and then had a tent peg put through his head.

Shortly afterwards an Oxford history don, Dr Robin Grey, is found dead with his eyes stabbed out in a similarly aggressive manner. Later on his old friend and fellow academic Simon Lake was discovered beheaded. It was clear that the killer was trying to send a message with the methodology and after plenty of twists, turns and red herrings it later emerged that the perpetrator was Ruth Astor.

She had one very traumatic and horrific reason for killing all three men - one that Morse, although not condoning what she did, sympathised with greatly. Ruth and her friend Eve Thorne, who was a model, dancer and sex worker to earn money, were booked to attend Robin Grey’s stag do a year earlier at the Shiplake Chase hotel. 

SHAUN EVANS as Endeavour and ROGER ALLAM as Fred Thursday.


This was attended by the secret society, The Berserkers, which Robin and Simon had both been members of. They had brutally assaulted and humiliated Ruth before Eve had come back into the room and threatened them with a knife to let her friend go, promising they’d pay. She’d taken Ruth to Eddie Nero and told him to “make it right”. He’d given Ruth a job as a telephonist and it turned out this was how rendezvous with the women he managed were booked.

“The client gets the girl’s name and number from a contact book,” explained Morse coolly to Eddie Nero, who pretended not to know what he was talking about. “Same kind of contact book I found in Joey Sikes’ flat. He calls and leaves a message for Eve or Jezebel or whichever belle de jour takes his fancy with an answering service.”

SHAUN EVANS as Endeavour


Each man rang up and left a message for one of the women and the women picked up their messages periodically to find out where to go. This was how Ruth had found Lake and Grey as she’d recognised their voices when they rang up to request Eve to visit them. She’d killed Joey Sikes because he’d driven her and Eve to the hotel that terrible night.

Ruth had been inspired by the scenes of "vengeful women" from the bible painted by Artemisia Gentileschi including Jael and Delilah. Having realised Ruth had been responsible, Eve had given Morse the slip from her house and headed to the home of one of the other men who’d been at the stag go - Adrian Croxley. 

ROGER ALLAM as Fred Thursday


By the time she got there he had been killed and Ruth had harmed herself. Morse and Thursday arrived soon afterwards and though they tried to get Eve to let Ruth go so they could get her an ambulance, she died in her arms before they could do so and had apparently not wanted medical attention. 

Thursday had been looking through the list of temps who’d worked a wedding at Shiplake Chase recently when silverware bearing the initials SC had gone missing. He’d recognised Ruth’s name and worked out separately to Morse that she’d gone back to get the silverware ready to kill the men. 

At the end Chief Superintendent Bright asked if there was anything they could charge Eve with since she knew that Ruth had been the killer. Morse defended Eve, saying he didn’t believe she’d been sure about that. When discussing Ruth’s death, Bright wondered if she couldn’t live with what she’d done, whilst Morse said, “Or what had been done to her”, reminding Bright of what Ruth had experienced as the Endeavour Muse episode came to a close.

What happened to Grand Duchess Anastasia’s Fabergé egg? 

Alongside and entwined with the murder investigation in Endeavour Muse is the matter of the Fabergé egg. At the beginning Dr Grey gives a talk about the one made for Grand Duchess Anastasia of Russia that was smuggled out. Called “Innocence” it was about to be sold when it mysteriously disappeared. It later emerged that Grey, Lake and artist Gerard Pickman who Eve had been modelling for had all served their National Service together and had acquired the egg at this time. 

ROGER ALLAM as Fred Thursday


Without any authentication they couldn’t sell it then, so they waited and Pickman falsified provenance documents for the egg. Grey authenticated them and they were going to all pull off an insurance scam and pretend it had been stolen by an outsider but before Pickman could collect the egg and hide it, it had been taken by Ruth after she killed Lake.

She’d later sent it to Eve inside a chocolate Easter egg with the message, “Buy yourself a new life and live it for both of us. R.”

Where did Joan go and why did she come back? 

Joan Thursday in Endeavour made her return in Endeavour Muse after leaving her life in Oxford behind her and moving to Royal Leamington Spa in Warwickshire. Before this episode, she’d fallen for a married man and later became pregnant by him, but he proved to be abusive and left her with nowhere to go. After she fell down the stairs she ended up in hospital, where she experienced a miscarriage and they called Morse. He never told Fred about what had happened and Fred had been angry enough when Joan left Oxford in the first place.

In Muse, she bumped into Morse and told him she was back but not “home”, as she wasn’t living with Fred and his wife Win anymore. Instead, she’d found herself a flat with two girlfriends, seemingly wanting to return to somewhere she felt was truly home and safe after all she’d been through. After barely speaking since she’d come back, Fred tried to talk to his daughter about how all he’d ever wanted to do was protect her from the wickedness in the world.

SARA VICKERS as Joan Thursday


To which she responded that it was 1968 and she was no longer his little girl and had to be allowed to make her own mistakes. Although they might not have resolved their differences then and there, this was a huge step for Joan and Fred in this episode after not seeing each other for so long. 

If you or someone you know finds themselves in need of support or someone to talk to in a safe space, they can reach out to Samaritans 24 hours a day by calling 116 123 for free or by visiting the Samaritans website and can reach out to Rape Crisis England & Wales by calling 0808 500 2222 for free or visiting their website. In the US call or text Samaritans at any time via 988 or visit the Samaritans website.

Emma Shacklock

Emma is a Royal Editor with eight years experience working in publishing. Her specialist areas include the British Royal Family, ranging from protocol to outfits. Alongside putting her royal knowledge to good use, Emma knows all there is to know about the latest TV shows on the BBC, ITV and more. When she’s not writing about the next unmissable show to add to your to-watch list or delving into royal protocol, Emma enjoys cooking, long walks and watching yet more crime dramas!