Kit Milcourt - impatient, quirky, idealistic and brilliant - has been a climber, diver in exotic waters and affluent young city banker. Now, because of his beloved Anna, he is a teacher. Glumly mediocre Sandmarsh High School, reeling under assaults from Inspectors and its own unpromising pupils, is hard put to contain his maverick ideas. Year Seven, on the other hand, love them. Only the soothing presence of Anna keeps the peace.

But Anna can't guard her erratic husband on the school trip: instead a far darker, more malevolent staffroom presence crosses Europe and discovers what Kit has secretly planned for the children amid the dim alleys of winter Venice. But children are unpredictable too, and things move rapidly beyond both teachers' control.

Between farce and tragedy the resulting events swiftly change Kit's and Anna's live in unthinkable ways, strain a great love to the limit and open a dark chasm into the past.