Ein gewisser Katulla (1974)

Late at night, a guest checks into the small hotel "Zum Spreewald-Idyll". The man seems suspicious. And he becomes even more suspicious over time. That's why they don't just call him "Katulla", he's "A certain Katulla". And he is not suspicious because he is suspected of evil, quite the opposite: he is suspicious because of his boundless helpfulness and kindness. Katulla is still kind even when he has to suffer disadvantages as a result. That's just not normal. So it is only normal that everything in the small hotel has been abnormal since this Katulla appeared.