Phonomanie [Russian]

A masked man in a suit gains access to an apartment; secretly, systematically and silently kills everyone present in a bestial way. Unnoticed, he leaves the scene. On a weekend trip some time later, Samantha and her friends realize that this incident was probably not the only one, because the culprit has left a trail of horror. Without further ado, they decide to do some research on the matter themselves, without realizing what they are going to do for a chain reaction.