I really wanted to love this movie. It promised all the Agatha Christie like elements I love. Secrets to be revealed. An eclectic group of very flawed characters in a confined setting. Class differences. A spooky mansion. Dark humor even.
But we quickly lurch into blandness and predictable plotting. It does not help that eight of the 12 characters are sent away at around the 20-minute mark after abruptly revealing their not very creative secrets. I had wanted to know more about each of them. After there abrupt departure some crosses and double crosses. And a series of flashbacks, one with very strange CGI, and a few bedroom scenes, one of which might be a bit of a surprise to some viewers.
The acting is community playhouse level. Madame Orlofsky, the psychic, (Triin Lellep) has an especially silly "Russian" accent and with the overacting reminded me of Natasha in the Rocky and Bullwinkle cartoon. The screenplay is full of plot holes, the directing pedestrian at best. There is not much in the way of visual interest in the sets. The characters are bland, not as villainous or "off" as they should have been.
Any positives? I understand that parts of this film may be a homage to the Hammer films of the 1950s and 1960s. Maybe. I've watched most of them, and this really too much of an inside joke for me to get.
The only mystery is why The Sixth Secret called a horror. I note a number of reviewers here use the term, as do some of the synopses on other sites. Odd. It's hardly horror. More mystery, sort of, and lame dark comedy.