House of Time streaming

Robert d'Eglantine invites five of his friends to spend a week-end in his castle, lost in the woods. He explains to them that he studied secret documents on nazi scientific research during World War II. These researches were on time travelling and he's now able to take his guests into an amazing trip seventy years back in time, in 1944, during the Occupation and only a few weeks before the landing in Normandy. The demonstration seems to be a big joke but once in the past our characters will be facing troubling events. Real time travel or devilish game meticulously crafted?