Evil Under the Sun (1981, released 1982, Guy Hamilton)

Peter Ustinov (as 'Hercules Parrot'!), Maggie Smith, James Mason, Jane Birkin, Colin Blakely, Nicholas Clay (with a widely variable accent), Roddy McDowell, Sylvia Miles, Dennis Quilley, Diana Rigg, Emily Hone (awful).

I'm not sure it was a good idea just to use music by Cole Porter.
Chris Challis shot it around the hotel on Cap Formentor, Mallorca (though it looks different now), a classy location doubling for the puzzling sounding 'Tyrrenhia'. Agatha Christie's original location in her 1941 novel was a hotel in Devon, so that was a definite improvement.

It's all a bit plummy, and not terribly interesting.