A lesser Christie story in a distinctly lesser adaptation.
The trouble starts with "The 60s". Christie published the book in 1961 but was still writing classic Christie-style stories that really only work to their best in a pre-war setting as per Suchet-Poirot. Hickson-Marple got away with the 50s by pretending little had changed since the 30s (and had the sense to set the 60s Marples in their version of the 50s alongside the others) but in both cases the result was the same: a comforting historical atmosphere that can make some poor plotting and characters forgiveable. But few people have charming fantasies about the 60s so the story has to hold the attention that much more securely: a tough job even with a major story and/or well-loved characters, both of which this film lacks.
The attempt at doing the 60s in this case is also pretty ham-fisted: book 1961, coffin lid 1964, mini dresses and knee boots scream 1967; hospital bedside electronics suggests 80s at least.
So with no convincing period atmosphere to fall back on, the weak plot with too few suspects and too many gaps is laid rather bare.
Even given these issues, all might not have been lost with stronger main characters but Colin Buchanan is simply not leading material. Jayne Ashbourne is arrestingly pretty and her easy naturalness could have made a great contribution given a powerful male lead and more dynamic script but as it is she just hovers unproductively.
In summary, it is watchable despite rather than because of itself but could have been much better for the same money if the producers had simply used a bit of common sense, set it in 1997, and spent the mini-skirt budget on a better leading man and a decent script editor.
