The late actor featured in murder mystery comedy Knives Out, which is being broadcast on Channel 4 at 9pm this evening. The film, which stars Hollywood heavyweights Daniel Craig, Ana de Armas and Chris Evans, sees detective Benoit Blanc summoned to the home of a wealthy author who has been found with his throat slit. Mr Blanc forms a bond with the deceased’s nurse Marta, as he investigates the dead man’s eccentric family in a bid to uncover the killer.

However, throughout his investigation an important question continues to irk the detective: who actually hired him?

Mr Plummer starred in the murder mystery as the deceased author Harlan Thrombey in what was to be the actor’s penultimate screen credit before his death in February 2021.

His career spanned seven decades, and included roles in a range of genres, from Shakespeare to Science Fiction. 

However, his most famous role is perhaps that of Captain von Trapp in the Sound of Music. 

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Throughout his career, Mr Plummer was a vocal critic of the Sixties musical, despite it helping propel him to international acclaim.

He told the Guardian in 2018 that the only reason he agreed to take the job in the first place was because he was working on his singing voice, and was looking for a film role that allowed him to sing. 

However, in an unearthed 2012 radio interview with NPR the actor surprisingly revealed that it is not actually him singing in the film. 

Mr Plummer said: “It was very well done.  

“So yeah, they did it very well because it sounded very much like me.”

Mr Plummer was frequently critical of the Sound of Music, and according to the New York Times, wasn’t even fond of referring to the film by its proper name. 

Instead he reportedly referred to it as either ‘The Sound of Mucus’ or ‘S and M’.

He explained to the Irish Times: “It was so awful and sentimental and gooey. 

“You had to work terribly hard to try and infuse some miniscule bit of humour into it.”

The actor was only on set for 11 days, however, and spent that time drinking and eating pastries.

Mr Plummer told Vanity Fair: “I got so fat, when I got to shooting Robert Wise [director] said, ‘My God, you look like Orson Welles.

“We had to re-do the costume.”

However, the role helped establish a 50-year friendship between Mr Plummer and Ms Andrews.

They would go on to work together again in a live theatre tour and on television, while their families are also thought to be close.

Watch Knives Out tonight at 9pm on Channel 4.