The Stone of Destiny

A cape wearing man joins the crowd at Stonehenge to see the Summer Solstice. When everyone goes home he travels to London to deliver a very important message to someone from his past.
This is no ordinary man for he is 500 years old. His name is Gilbert and he is Eleanor Pritchard's long lost brother, whom she thought had died hundreds of years ago.
Gilbert arrives at the Pritchard home and tells his sister that the power in the talisman has faded. Mother races to the talisman which she keeps in a safe and when she takes it out sees that all of the five rubies have gone brown. The family realise that William breaking his arm at university has made the talisman powerless. Gilbert tells them they must find a very special stone, the only stone that will restore the full power back to the talisman so they can bring their father home from 1851. The problem is, this special stone is placed under the chair of every king and queen's coronation in England.
It's the Pritchard's first time travel adventure as a family to find the stone, however, not only do they have the evil Raven after the talisman, but other darker forces are also after it.
It's a race against time for the Pritchard's. How will they find the stone and which era in history must they travel to first? Will this be the stone of their destiny?