Jane Barlow Schwartz is obsessed with one question: why did her best friend Martha stop being her best friend? The two girls, distant cousins, had shared idyllic childhood summers in the New England seaside town of Barlow, named after their family's founding fathers. Martha was not just Jane's best friend but her idol, her soul mate, her confidante. Then, somewhere along the line, the friendship ended. What went wrong? Was it the family feud, which their parents spoke of only in hushed tones? What did Jane's dotty great-aunt reveal to Martha on her deathbed? Did Jane do something unforgivable?
When the cousins are reunited unexpectedly on a tour of the Galapagos, they meet Darwin head-on. In the pristine Pacific waters, amid blue-footed boobies and red-lipped batfish, Jane traces back through her Yankee-Cuban-Jewish ancestry to try and pinpoint the "splitting event"- the moment when Martha was no longer the Martha she knew. In the process, she ponders the origin of species and the origin of friendship, the instincts of exotic wildlife and of her eccentric shipmates, the evolution of nature and of her life.
