Based on a play by Bella and Samuel Spewack
A lot of the movies I review here fall into a zone that I'd categorize as not spectacular, but not so lousy that I felt like my time was wasted. Which was the case with The Solitaire Man (not to be confused with a recent Michael Douglas movie called The Solitary Man).
It stars Herbert Marshall as Oliver Lane, head of a gang of jewel thieves who's decided that it's time for him to go straight. When one of the other gang members doesn't get the memo and makes off with some jewelry, Marshall takes the drastic step of trying to return it without being noticed. Unfortunately, while doing so, a Scotland Yard inspector is bumped off by person or persons unknown and the plot thickens considerably.
Which accounts for about the first one-third of the movie and which is not all that riveting, to be quite honest. Things pick up a bit as the proceedings move to a small passenger plane traveling from Paris to London. The passengers are the four jewel thieves, another Scotland Yard inspector (apparently) and a loud-mouthed American woman. While I wouldn't go so far as to say that the wrap-up was particularly spectacular, it wasn't all that bad either.
Here's a New York Times review of the movie from back in the day.