It’s technically known as ‘life review’, the moment when someone’s life flashes before their eyes during a near death experience. Never having been afraid of the rarefied air of high concepts, Inside No.9’s Reece Shearsmith and Steve Pemberton decided to film that very event, putting us inside the head of Christine (Sheridan Smith) as she lies dying following a road accident.

Not that we, or Christine, knew that at first of course (this is Inside No.9, always served with a twist). The 12 Days of Christine took us across 12 separate days, across 12 different (chronological) months, over 12 years of Christine’s life – from the New Year’s Eve party where she met future husband Adam, to an unsettling Mother’s Day, a heart-stopping Halloween and the final, fatal, Christmas Day. As we progressed through time things, and Christine, began to unravel, bringing to mind Eternal Sunshine of the Spotless Mind or Iain Banks’ The Bridge.

This offering was low on the laughs and high on the chills as Shearsmith and Pemberton slowly ratcheted up the tension, day by day, starting with confusion over a Valentine’s Day card from a childhood boyfriend before genuinely bowel-emptying moments involving eggs and Blind Man’s Buff. The egg scene – alone in her flat, Christine begins to see raw eggs splatted against the walls and floor – is as terrifying as anything Shearsmith and Pemberton have come up with before and suggests that a full blown horror film would be well within their capabilities.

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The 12 Days of Christine is as much about relationships as it is about death, with Sheridan Smith and Tom Riley excellent as the once happy couple whose relationship is pushed to breaking point before snapping. People who have experienced ‘life review’ talk not only of reliving moments of their life but of being able to see and understand the repercussions of their actions, and as we career through Christine’s time on earth (a re-watch of this episode is recommended) we can see her attempting to snatch at lost moments and longing for second chances.

It’s a credit to the two creators that they can pack in such a depth of emotion into 29 minutes, with the final scene providing a real lump-in-throat moment as Christine says goodbye to her family for the last time. The star of the show this time round however is undoubtedly Smith, who at the tender age of 33 must be a contender for Britain’s Youngest National Treasure. It’s fair to say she’s come a long way since the seemingly endless Two Pints of Lager and a Packet of Crisps.