Geordie Plays Detective with Alphy's Past in 'Grantchester's Penultimate Episode

Cece's Boutique's grand Saturday opening is three days away as Grantchester's penultimate episode of Season 10 kicks off. There are tons of things to do, from painting to lighting to curtains, not to mention cleaning and dusting, as well as signs on the doors, windows, receipts, and shopping bags. But most importantly, there's a photoshoot of the clothing to be featured in the Friday circular, which is when things start getting stressful. 

The photographer, Tony Parker (AJ Bentley), is a self-important jerk, but he isn't wrong in his professional assessment of this new venture. Kate Ashley (Ria Marshall), the clothing supplier, attempts to bring an entirely different line of clothing than initially promised, and only one of the models, Pheline Meyer (Ada Richardson), is professional; the other, Grace Tuffit (Kate Humbles), is yet another of Cathy's cousins. Sure, he orders Jack, Alphy, and Geordie around like staff, but he's on a tight turnaround here. Tight enough that the next morning, when Mrs. C arrives at the shop with Alphy, Tony is dead, shot through the heart.

It's the fastest the show has gotten to the body in a minute, and it's a reason to panic that the store won't open now. It's also a murder case that serves as a welcome distraction for Alphy, because now Geordie has more to focus on than the letter from his mother they opened at the end of last week.

Tony has provocative photos of Pheline in his pocket, but it's Kate Ashley with whom he's in some kind of relationship. She's sporting a black eye from a fight (she claims she "fell"), and has rolls of Tony's camera film in her flat, which she willingly destroys, assuming Inspector Keating is there to take them back because Tony reported them stolen. She is pretty shocked when she learns he did no such thing, and won't ever again. Down at the station, she admits she lied, and Tony did come by after he had discovered she'd stolen and destroyed all the pictures from the shoot. (So even if he'd lived, they wouldn't have made the Friday paper.) But she didn't kill him.

All this means the dress shop's a crime scene, and the photos Tony took never made the paper, so Mrs. C and Cathy take themselves to Daniel to beg for last-minute photography help. He's supposed to be doing family portraits and agrees to call in sick to reschedule them, as well as take pictures for the advert campaign in the meadow, since there's nowhere to do it in the shop.

Meanwhile, there's an entirely different lead from a completely different case to consider. Larry and Jenny have been working on a case involving the theft of a £3,000 diamond, while Geordie has been helping with the boutique. It turns out the diamond was stolen on the way back from being photographed by our now-dead photographer. Kate might have means and motive over some clothing images, but a diamond's a much more likely reason to knock a bloke off.

Geordie and Alphy pop by the outdoor photoshoot to poke about and ask Grace and Pheline if they knew anything about Tony's other photoshoot, or if Kate might have. Unfortunately, Pheline is not there; she beat a hasty retreat at seeing that Daniel was the new photographer, and her German farewell caught his attention enough that he's probably worked with her before. (Longtime Grantchester fans will recall that Daniel started his career taking photographs that were slightly less than PG, and it's a good bet Pheline was a client.) 

Cathy is enraged at the interruption, but Geordie's right, they have to do it by the book. Grace went out with Tony after the photoshoot and is expecting a second date tonight, which is awkward. He promised to take her away to London and everything, and she was green enough to believe him. Perhaps its for the best he's dead. 

As for Pheline, Geordie decides they should go by Tony's place first before tracking her down, and it's the right call, because his flat is where they find her, fighting with a large red-faced gentlemen by the name of Brian Halliday (Clive Brunt) as they desperately search the flat for the diamond. (Geordie's trick of pretending one of the ice cubes in his drink was a "rock" to get them to admit what they were fighting over was particularly sly-old-doggish.) 

Pheline pretends that she was only there for "her portfolio," but when Daniel shows up with other photos of her (Called it!), she's forced to admit that she's not even German, and her name is Phyllis Morgan. Lucky for her, Phyllis Morgan also has an alibi, as she works as a waitress in a pub, and her boss can confirm she was on shift from 8 p.m. until close. Alphy has a feeling that Halliday's alibi will also check out, and everyone assumes Cathy and Mrs. C are innocent (plot armor baby!), which leaves two suspects: Grace and Kate.

With the shop unfinished, Mrs. C has a brilliant idea of making Saturday a soft opening with an invitation runway show. Cathy, who already has no control over anything due to the murder, flips out at more last-minute changes, though one hopes she comes around on this one. Their argument occurs as Geordie is in the next room on the phone with his old buddy Cecil. Since the coroner's report won't be in until morning, he's chasing more leads on Alphy's mum, despite Alphy's request that he stop.

But Geordie's not having a good day either, as Mrs. C starts crying because the coats Kate delivered are falling to bits and there's still a feather boa missing. Geordie knows David stole the boa and finds it in the kid's backpack. Leonard, Jack, Alphy, and Mrs. C all hear him nearly call the kid... well, let's assume it was not the f-word, but something more 1950s slang, like pansy. Not that that's the slightest bit better.

Geordie did do one thing right: he called Esme to come stop by now that she doesn't live at home and show her mother how much she's learned. ("Don't recreate your home life at work" is legit a piece of advice I could have used at her age, and I am thrilled Esme has a boss who's sharp enough to say it.) Cathy takes her lumps at being told not to treat Mrs. C like her own children, and that the best thing she can do is encourage others to be their best while she does the same. When she arrives at the shop, there's a runway and everything is ready to go, with the clothes on display as Jack and Leonard prepare the champagne glasses for the invited guests.

Meanwhile, Alphy sits Geordie down to try to discuss the David situation, only to have it turned back around, as Geordie says he doesn't understand any young men today, not David and his doodles and dreams, and not Alphy's refusal to find his mother.

With all this emotional drama, it's a wonder anyone has time to solve the case, but hey, that's apparently what Larry and Jenny are for. Larry tracked down Tony's plans, which involved a single ticket to the Caribbean, where he'd disappear. Except there was someone who'd believed she was going with him: Grace. Grace, Cathy's cousin from the sticks, who lives on a debt-ridden farm with her mother and brothers after her father ran out on them. Grace, who knows how to shoot a rifle, was modeling the coat that Mrs. C. had noted had a torn lining —a coat large enough to fit the long weapon.

Grace is a sharp one, insisting she doesn't hate her father for leaving; she's just sad. And yes, she wants to escape, but not to the point of hurting anyone. So, Geordie and Alphy devise a plan once again to make the suspect think there's a diamond. This time, it's Larry holding a little velvet bag, playacting that he's found the diamond and is going to enter it into evidence, before tossing the bag on his desk directly in front of Grace and walking away. Poor thing falls for it, hook, line, and sinker.

Grace admits she's guilty and has been arrested, but not to worry, Cathy's already solved her problem of being short a model. Pheline is still up for walking the show, and with her is another new model, whom she'll train up: Miss Esme Keating. Not only does Esme rock the cute little frock she's modeling, but it turns out those pockets are pretty handy for hiding...and finding...a diamond. That's two cases solved, and one fashion show pulled off.

Additionally, Geordie managed to speak with David briefly, without shouting at him or otherwise telling him to be a man, so that's an improvement. The boy claimed he wanted the boa feathers for fishing lures. (Ok, fine, sure, whatever you say, kid.) Also, Alphy invited Meg to the fashion show "as purely platonic friends." (Ok, fine, sure, whatever you say, kid.) Unfortunately, when he goes up to Cathy to congratulate her, she congratulates him too on Geordie finding his mum.

Not the best way for Alphy to learn that one. Of course, the news goes over like a lead balloon, even when Geordie explains it's only the last known address; he hasn't found her. Alphy lashes out hard and tells Geordie off. Esme's going to have to pull some more magic to make her dad apologise next week.

Grantchester Season 10 continues with the finale episode on Sunday, August 3, 2025, at 9 p.m. ET on most PBS stations, the PBS app, and the PBS Masterpiece channel. All eight episodes are available to binge on PBS Passport for members. As always, check your local streaming service/listings. Seasons 1 through 9 are also available to stream on PBS Passport. Grantchester has been renewed for its eleventh and final season, set to air in 2026.