I stumbled across this Polish film on Amazon Prime and started to watch it. I then kept watching it until the end - my usual approach to films. Medium is pretty good, not least because it defies most of the expectations of a Western horror fan.
The story is set in Sopot in 1933. Sopot is, I have since learned, on the 'Polish riviera' and is part of a tri-city complex with Gdansk and Gdynia. It certainly makes a beautiful and fascinating setting. In 1933 it was part of East Prussia, and Hitler had just seized absolute power. The film leaves no doubt about this, with a regular diet of posters and Brownshirts.
A female medium and her astrologer brother are attempting to detect a rival psychic. All they know is that he is controlling a group of seemingly random individuals. A bearded man in a hat and trench-coat wakes up on a beach. A dapper man arriving by train seems to be in a trance. An attractive teacher abandons her pupils and goes to a museum to steal a red dress.
It's all very Eastern European cinema, dear me yes. But interesting. And all the action revolves around a suitably spooky old house. This one, in fact.