The volumes of the Parallel Worlds series can be read independently.
David has a dream, but not any dream, a dream that seems so real that makes him what is more real, my daily life or the dream I have just had? During the dream, in turn, a strange journey in time and space happens. A young hiker in Teotihuacán (United Mexican States) seems to be connected with a Spanish student in London. The mysterious archaeological site of Stonehenge is to blame for the young woman to fade and leave who knows if to another reality, perhaps there are connections between all the archaeological sites of the world.
David wakes up from his lucid dream, having the feeling that when he wakes he enters a reality "less real" than the dream one. The search continues, who has made a trip to a parallel world wants to know more.