Usually Lino Ventura plays a tough gangster or police detective, without doing not much besides frowning and looking pensive. But he COULD do much more, like comedy (Monsieur Gangster) and there are also a couple of films in which he had to endure stuff in a godforsaken spot somewhere on earth. I tend to think those were the films he really loved to do, for example Greed in the Sun, Le Ruffian, Les aventuriers, and this one, in which he gets his hands really dirty. He plays an experienced captain and has to do a lot of hard labor, diving deep, carrying crates, pulling ropes, pulling a heavy lever, dodging bullets, et cetera.
The film is set almost completely on a boat and an island, which is quite remarkable. A pleasurable watch, although it is not THAT GOOD. The main problems are a few plot holes (how about opening one of those boxes!), a predictable storyline and the part of Leo Gordon, who is a bit too old-fashioned as an actor for this film. And there is not a lot of chemistry between the characters Osborne and Cournot but I am not sure if that was intended anyway.
Predictable or not, I liked it, not only because of Ventura, whose films I almost always like (and there are plenty), but also because of his female counterpart, Sylvia Koscina, an underestimated actress who was not only pretty but also quite good in acting, and played in a lot of interesting sixties flicks in all kinds of languages, like Giulietta degli spiriti, Hot Enough for June, Deadlier Than the Male, Judex, to name just a few. But it was also a decent directed film by Claude Sautet, for whom this is NOT AT ALL a typical film (just watch for example Un Mauvais Fils to get an idea), and shows he was also capable of some easy entertainment. Even better is Classes Tous Risques made five years before this film, also with Ventura, and of course doing rough things. I rate this 7/10.