If anyone doubts Graham Norton's position as chatshow king, a look at tonight's opening line-up should set them straight. While Alan Carr has the solid if unspectacular likes of Lionel Richie, Jessie J and Nick Grimshaw over on Channel 4 (10pm), Norton's sofa dwellers - Denzel Washington, Gemma Arteton and new Doctor Who Peter Capaldi - offer real big-name clout. Music, meanwhile, is provided by the endlessly emoting George Ezra, whose croaky folk has proved inescapable this summer.

Gemma Arterton to star in Made in Dagenham musical

Gemma Arterton is to star in a musical version of Made in Dagenham.

If they could only write faster, Steve Pemberton and Reece Shearsmith could have a golden age all to themselves. After Psychoville, they have knocked out Inside No. 9, a series of short stories each set in a different No 9 and steeped in their trademark dark humour.

The third No 9 is a flat occupied by Shearsmith's Tom, a primary-school teacher, and Gerri, an actress played by the actress Gemma Arterton. Once you've got over the idea that someone as tall as Gerri would go out with someone as short as Tim, it's all perfectly plausible.

A tramp returns a wallet to Tom, Tom lets the tramp come in for a drink and the tramp takes over his life. Gerri movies out. Tom becomes a tramp. The tramp becomes Tom. Like the best of Roald Dahl, we've been lead, incrementally, plausibly, from a normal state of affairs to the unbelievably bizarre. I won't' tell you how it ends because it's till on iPlayer. Binge away.

Episode three of the superb anthology series, and following the clownish antics of the last episode we're firmly back in Tales Of The Unexpected territory. Frustrated schoolteacher Tom (Reece Shearsmith) yearns to carve out a career as a writer, but finds his aspirations dampened by the need to support the acting career of his partner, Gerri (Gemma Arterton). A chance favour from a dishevelled stranger sets his life on a different, much darker path. The highlight of the series so far, with Shearsmith and Steve Pemberton on top form.

Less comic, more deep and dark, tonight's No.9 takes us to a flat occupied by teacher Tom (Reece Shearsmith) whose aspiring actress girlfriend Gerri (Gemma Arterton) is heading off for an audition when we drop by. It's the start of a game of cat and mouse, with Steve Pemberton as a homeless man who looms ever larger as the tale twists and doubles back on itself in sinister fashion. You'll want to press the replay button to search out the subtle signposts you missed along the way.

Radio Times review

The No 9 we visit this week is the flat of Tom (Reece Shearsmith), a primary school teacher whose disdain for hard work contrasts with his sunny, beautiful girlfriend Gerri (Gemma Arterton) and her efforts to make it as an actress. Tom keeps peeking scornfully out of the window at a homeless man in the street, until circumstance brings the vagrant, Migg (Steve Pemberton), into the flat while Gerri's away on a job. The gimmick of the show is that we never leave No 9, and maybe the persuasive Migg won't, either.

By halfway you'll have confidently announced where it's going, but Shearsmith and Pemberton give their story of how we're all one slip away from the gutter a chilling sense of rising dread. Nobody plays wicked games with the audience more skilfully.

Inside No. 9 Episode 3: 'Tom and Gerri' review

With sterling support from Gemma Arterton and Conleth Hill as the most important people in Tom's life, this is a tightly scripted half hour that has much in common with a stage play.

Inside No. 9 looked at life behind closed doors. After last week's silent-movie hijinks, it was back into the darker recesses of its creators' psyches.

It's always trepidatious when Reece Shearsmith dons the clothes of an ordinary man - something wicked this way comes.

Here we started with Tom, a clean-cut primary school teacher, and his girlfriend (Gemma Arterton). Tom rapidly descended into an almighty funk with the help of a homeless man called Migg (Steve Pemberton).

What began as a study into the unspoken horror of Tom letting the filthy Migg into his house, took a turn for the darker as Migg slowly imbibed Tom's spirit. Or did he? The timing of the "twist" that he didn't actually exist suggested early on that there might be more to come and there was.

This third episode wasn't really in the slightest bit funny, but that's no complaint - I found myself moved by its sad brilliance. Its ambiguity about Tom's state of mind a fine - if cartoonish - take on mental illness. It also featured the glorious line: "You're not Charles Bukowski, you're just a primary school teacher who had a nervous breakdown." So that's one laugh, at least.

Reece Shearsmith and Steve Pemberton interview

"When Gemma Arterton said yes, we were quite surprised, because she's a big movie star. She just said, 'Well I don't read scripts like this' and that made us feel very excited."

The sainted Delia Smith takes her place on the sofa tonight, just one ingredient in a rich mixture of guests. The Hollywood shimmer comes from Jeremy Renner and Gemma Arterton, who'll be talking about their new film, Hansel & Gretel: Witch Hunters.

Matt Lucas, now a bit of a film star after his turn in the hit Bridesmaids, is in comedy corner, where doubtless he'll want to talk about the return of his BBC1 series, The Matt Lucas Awards. Rita Ora is the musical guest.