Mockymen — Ian Watson

When a young British couple, who make jigsaw puzzles, are hired by an ageing Norwegian to take nude photos of themselves in a sculpture park in Oslo, they are drawn into a web of occult Nazi horror. Even more horrifying will be the fate of the whole world some years later if alien visitors achieve their secret aims.

However, the aftermath of events in that Oslo park will provide Anna Sharman with a key to unlock those aims.

Anna is a rebel within Britain's intelligence service at a time when most of the world appeases the aliens because of the gifts they bring - and if she must lose her own body in order to discover the truth, she will do so.