Along with the Tsar, those who were thought to have died that morning included the Tsarina Alexandra Feodorovna, his son Alexei Nikolaevich and his four daughters, Olga, Tatiana, Maria and Anastasia.
But some believe that Anastasia might not have perished at all. An extraordinary new theory suggests that she may have escaped and that DNA evidence which was thought to have proved she died is flawed. We'll explore and find out.
Was the infamous imposter Anna Anderson actually telling the truth? What really became of the Grand Duchess Anastasia? Were that family secretly exchanged in a Soviet - German pact at the end of World War One?
A fascinating - and disturbing - investigation is on the horizon...