This film is a decent little thriller with some lovely period yachting sequences -- it wasn't quite what I'd expected, which is probably a point in its favour. The running time feels briefer than its actual 80 minutes, and there really isn't much space for subtleties; the film leans happily on every post-war cliché going, has no room for red herrings or false leads (the treasure quest really is remarkably straightforward!), and makes good use of its one big mystery, Who Is Helene (and what is she really up to?)
One interesting twist is that since the cast are all of them supposed to have been on active service during the War eighteen years earlier, none of them, even the two women, can be played by youthful starlets. For me Ronald Howard stood out as the avuncular Bill Webb, whose kindness and good humour help keep things calm; there is a small romantic sub-plot between Pru and David, the younger two (which is to say that they are probably not yet forty), but the film doesn't waste too much time on that. We have Incredibly Evil Nazis, stolen treasure with a map in multiple parts, the undercover radio operator leaving the tap running to cover the sounds of the Morse key (which is of course a heinous crime in its own right on board a yacht with limited water-tanks, and I was relieved to see the script point that out!), treacherous quicksands, sinister thugs (whose identity I don't think is ever explained, unless they were in fact simply the port police), a secret vault inside which one can become trapped, and a slightly jaw-dropping amount of alcohol being served out at every opportunity.
The twist at the end is well executed and took me for one completely by surprise; my stomach lurched in anticipation of one dramatic irony, and then we ended up with a completely different turn of events. (And that's about the one part of the plot that does actually get a scene afterwards explaining how it worked, which was obviously felt to be necessary -- given the 'convenient coincidence' attitude of most of the rest of the action, I don't think I would have questioned it myself!)
The twist at the end is well executed and took me for one completely by surprise; my stomach lurched in anticipation of one dramatic irony, and then we ended up with a completely different turn of events. (And that's about the one part of the plot that does actually get a scene afterwards explaining how it worked, which was obviously felt to be necessary -- given the 'convenient coincidence' attitude of most of the rest of the action, I don't think I would have questioned it myself!)