Ordeal by Innocence: BBC's gripping Agatha Christie drama is well worth the wait

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When we meet them, the Argylls are recovering from a spot of Unpleasantness. Eighteen months ago their heiress mother Rachel Argyll (Anna Chancellor) was brutally murdered at the family home. Despite protesting his innocence, her adopted orphan son Jack (Anthony Boyle) was arrested for her murder and died in prison.

All rather unfortunate – but very neatly resolved and firmly in the past.

Now, Leo Argyll (Bill Nighy) is about to tie the knot with his obnoxious secretary Gwenda (Alice) and has gathered together his four surviving adopted kids, Mickey (Christian Cooke), Hester (Ella Purnell), Tina (Crystal Clarke) and Mary (Eleanor Tomlinson), as well as his son-in-law Philip Durrant (Matthew Goode) and housekeeper Kirsten (Morven Christie).

But then a bombshell hits: Jack's long-lost "alibi" Arthur Calgary (Luke Treadaway) turns up at the Argyll mansion to proclaim his innocence. Is this true? And if so, who really killed Rachel?

As you can tell from this brief run-down, there are many, many familiar faces in Ordeal by Innocence. But one face is missing. In a vault somewhere exists a scrapped version of Ordeal by Innocence with one crucial difference: Mickey Argyll is played by Gossip Girl's Ed Westwick, not Christian Cooke.

For those who missed the headlines, Ordeal by Innocence was originally intended as the BBC's big Christmas production, but in November Westwick was accused by two women of sexual assault (allegations which he denies) and the drama was pulled from the schedules.

To rescue the project, producers decided to take the Kevin Spacey/Christopher Plummer approach and reshoot every single one of Westwick's 35 scenes with a brand new actor just in time for Easter.

So can you see the stitches? Absolutely not.

In fact, you'd never know that Cooke hadn't played Mickey all along. The summer scenes in the garden still look lovely and sunny, even though they were re-shot in January and February when the weather was so cold that you could see people's breath (a continuity challenge for the production team). Nothing jars about Cooke's version of Mickey, or about how all the other characters react to this newcomer in their midst. They've pulled it off!

And on the subject of those other characters: they're all so deliciously awful.

Whether Jack is innocent or not, Cursed Child star Boyle can produce the kind of creepy laugh and smile that would send small children running to their mothers. Philip, angry at his confinement to a wheelchair and his reliance on wealthy wife Mary, exudes malice with every carefully-chosen word. And as for Gwenda, she's a cartoonishly evil wannabe stepmother: she may look like Glinda from the Wizard of Oz, but she's no Good Witch.

Sarah Phelps' adaptation plays with the audience, slowly revealing pieces of the puzzle and toying with our expectations. The grand Argyll house at Sunny Point is certainly idyllic, with its trailing wisteria, sweeping staircases and rickety jetty over the water – but with each flashback to the kids' troubled childhoods and to the night of the murder, the dark undercurrent is revealed.

This is no paradise. Everyone has secrets, and at least one person knows the whole truth about Rachel's murder.

Christie purists may be alarmed to find that Phelps has played fast and loose with both the characters and the plot. Unlike in the novel, we don't see the story unfold through Arthur Calgary's eyes: instead we are invited from the very beginning to question his version of events. Jack's wife Maureen is out of the picture. The Cold War context is ramped up.

But honestly, this would be a boring TV adaptation if it stuck too closely to a story we'd already heard. New twists and turns were needed to bring it to life. And what twists and turns they are!

After the first episode we're desperate to return to Sunny Point – even if there is still blood on the carpet, and even if a murderer lurks within its walls. Like Arthur Calgary, we just have to find out what really happened.

This article was originally published in March 2018