Secrets of a Psychopath (2015)

Psychopathic siblings Catherine and Henry use dating sites to lure unsuspecting people to their home for sadistic games and inevitable slaughter.

And Then There Were None (1945)

Ten strangers are summoned to a remote island and while they are waiting for the mysterious host to appear, a recording levels serious accusations at each of the guests. Soon they start being murdered, one by one. As the survivors try to keep their wits, they reach a disturbing conclusion: one of them must be the killer.