Her Fearful Symmetry by Audrey Niffenegger

Elspeth and Edie were identical twins who had a major falling-out when they reached adulthood. Edie and her husband Jack moved from London to Chicago where they raised their twin daughters, Julia and Valentina. When Elspeth dies, she leaves her flat in London to her two nieces. It is a big surprise to them, since they never even knew that their mother had a twin.

Julia and Valentina are 21 when they move to London, planning to live in the flat for at least a year. There are two other flats in the house: Martin lives on the third floor and Robert lives on the ground floor. Martin battles such extreme OCD that he rarely leaves his apartment. Robert was Elspeth's lover of 10 years and is having great difficulty adjusting to her absence. The arrival of the twins has a big impact on both of these men. And Elspeth, who is now a ghost, stuck in her apartment, is in the middle of everything.

The plot gets downright bizarre, but I enjoyed following the twists. Towards the end, I was reminded of Niffenegger's illustrated novels, and could envision her aquatints replacing chunks of the text. Despite the melodrama, at its heart, Her Fearful Symmetry is an examination of consequences, especially the price we pay for lies and lack of fortitude. I liked it much better than The Time Traveler's Wife.