Inside No 9: Boo to a Goose, review: only a tiny bit weirder than your average night on the Tube

One of the smartest things about Inside No 9 (BBC Two) is that the stories are rooted in recognisable human behaviour, no matter how outlandish the plots. Boo to a Goose, the first episode of the ninth – and final – series, is a perfect example.

Imagine yourself in a train carriage, where a man begins behaving like a bully and assaults another passenger. Do you jump in to break it up? Decide that it’s none of your business? Or dither, wanting to step in but not being quite brave enough?

But I’m jumping ahead. We’re in that Tube carriage late at night, with a motley assortment of passengers. Gerry and Edith (Reece Shearsmith and Siobhan Finneran) are a respectable-looking couple.

Then we have scowling teacher Raymond (Mark Bonnar), sweet-natured nurse Elena (Philippa Dunne), obnoxious drag queen Wilma (Steve Pemberton) and sidekick Cleo (Susan Wokoma), doolally Harold (Matthew Kelly), and a paranoid man played by Joel Fry who doesn’t want to give his name because he says the state is spying on them all. Just like an average night on the Central Line, really.

There is also a homeless man (Charlie Cooper) walking through the carriage, politely and apologetically asking for money (if you’re a London commuter you’ll be very familiar with this speech). When the train comes to a sudden stop and the driver announces that there has been a power outage, meaning they’re stuck in a tunnel, things become oppressive.

Elena says her purse has been stolen, and a furious Raymond takes it upon himself to root out the culprit. Tempers flare. People take sides. Harold (Kelly) leavens the mix by bringing up his encounter with aliens: “They experimented on me at a bus stop in Preston.” This is Inside No 9, so you know that not everyone is exactly as they seem. But which of them is fooling us?

It plays out like a cock-eyed Agatha Christie, because we’re trying to work out whodunit without knowing what it is they’ve done. The twist is decent enough – I won’t spoil it for you if you’re yet to watch – although for my money it goes a step too far down the silly sci-fi route. Not a top-tier Inside No 9 episode, but a neat scenario and a welcome opportunity to see some of our best character actors having fun.

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