You are member of an international team of archaeologists who worked on an ancient site dubbed "Stonehenge". Some experiments had unfortunately activated the dolmen and all the team appeared millions of years in the past. You tried send message on a platinum tablet to the future. Somebody probably found it; a message arrived from future via Stonehenge. It contains an old prophecy: You must gather three artefacts in order to revert the polarity of the Stonehenge and return to the present. Artefacts are hidden even more deeply in past - the only way to reach them is to go through Stonehenge. What is the problem? Space-time paradoxes created at least two copies of you and your team in the different parallel worlds. Only one of them can return - the first one that manages to gather the Artefacts gets to return to their time.