Miles and miles of nothing but sand; huge dunes like golden mountains stretch as far as the eye can see, and a heat haze shimmers beneath the punishing glare of the desert sun. This is the sight that greets four travellers from the future when they arrive in the heart of the Rub’ Al Khali desert, otherwise known as the Empty Quarter.

As twins Jemima and Joe Lancelot continue the quest for their missing parents, together with best friend Charlie and their Tonkinese cat Max, they wonder why they have come to this place? Only Max knows the answer, for he has been here before…

Newly arrived in the port of 18th century Bristol, on a ship from the Caribbean, a young boy escapes from his master and is desperate to avoid recapture. Hoping to make his way to London, the runaway slave has no idea what to do next until he bumps into three other children who have also just landed in the city. Travellers of a different kind, this trio have not journeyed from another country, but from another time – the 21st century – and they will do all they can to save their new friend.