Kat has traveled with her teenage daughter to Lutrá, in Greece, where she must make a decision. Lutrá - "baths" in Greek - is the town of her father, who has just died. The natural pools that form under six small waterfalls trace the perimeter of the town. Its waters are said to have healing properties, and Kat soaks in them in the hopes that they will also have beneficial effects on her troubled heart. Upon her return, he will have to know what to do with her marriage, which she contracted when she was very young and has been deteriorating: it is no longer a matter of two. In order to come to a resolution, she follows the thread of her existence as she swims thirty-nine lengths, one for each year of her life. She needs a rational, scientific procedure: if she can discern the moment when her marriage ended, some scene, a definite point of the end, she will know what determination to make...