The novel is by turns romantic, philosophical, funny, sexy, and frightening, as the characters explore the different possibilities offered by their unique talent.

Both Peter and Amaryllis have been involved in failed relationships before – exactly how many and how disastrously we only find out gradually – and they are haunted by the danger of repeating their past mistakes.

Hoban's writing builds up a series of metaphors throughout the book so that, as in a dream, many things take on unusual significance, or seem to represent something else.

The hypothetical object known as a Klein bottle plays an important role in the book after Peter visits the London Science Museum.

This concept is built up in the book as a metaphor for the way people cross and re-cross important physical and emotional points in their lives.