A few years into their marriage, while their children are still young, Sara and Phil discover that he has an aggressive form of cancer.  He undergoes grueling surgery, but the cancer returns.  For Sara the prospect of Phil's death reawakens the trauma of losing her father when she was twelve.  Phil does his best to live a normal life between chemotherapy treatments and further surgeries, and even enters an experimental treatment in hope of seeing his children grow up.  His greatest pleasure in life is sailing, and one of his deepest hopes for his remaining time with his family to enjoy sailing with them in the ocean near their New England home.  But Sara finds it scary, even though she gamely learns to crew, and the kids never take to it.  So Phil sails with friends, and sometimes alone.  After learning that the cancer has continued to spread despite every medical effort, Phil decides to take one last sailing trip, this time alone, on the ocean.  There he has to make a decision:  his intention is simply to sail until his body gives out and die on the boat he loves, sparing Sara, he thinks, having to watch him die a slow and painful death.  But he begins to realize that letting her see him through might, after all, be a better way to go.  As the novel ends, he turns the boat, now quite far from land, toward home.