After the death of her twin brother and the loss of her longtime boyfriend, Greta Wells seeks the help of a doctor who suggests electroconvulsive therapy as a way to reset her mind and overcome her crippling depression. So on a November day in 1985 New York, Greta undergoes her first treatment and wakes up in 1918 New York. While some circumstances of her "new" life are joyful, she has new troubles and some of the same ones that haunted her in 1985. Her next therapy session sends her to 1942. Another session and she is back to 1985. While she goes about trying to "improve" her life in these other decades, the Gretas that she has displaced have also been working to make changes. 
 The concept is very interesting and while incredible, the author manages to focus the reader's attention on the characters and relationships rather than on the time travel. The ending is a surprise and wraps up Greta's final session in dramatic fashion. A very good read!