Memory is a great mystery. Why do we remember some things and not others? How is it possible for two people to experience the same event and yet remember it differently, or for one of them to have no memory of it at all? What if these two people happen to be married? And what if one of them happens to be dead? These are just some of the intriguing questions Rosecrans Baldwin raises in his poignant and very funny first novel, You Lost Me There (Riverhead Books, New York, New York; Hardcover; 304 pages, $25.95). They are especially important questions for the novel’s narrator, Dr. Victor Aaron, a pre-eminent researcher working on a cure for Alzheimer’s disease who can’t remember what happened in his own marriage. Victor, 58, has been a widower for two years. He is a depressed workaholic who suffers from fits of uncontrollable crying. He tells the same joke over and over; he doesn’t know the slang term for a sleeveless undershirt; his social life is pathetic. He is in mourning. But as the novel opens, he has just discovered an alternative story of his thirty-year marriage written by his deceased wife, and things in his life are about to change.

Set on Mount Desert Island in 2006, and filled with ample description of island life and landscape, this is a novel rich in character and incident. But what is most fun about it is seeing the world from Victor’s endearing, if somewhat skewed, point of view. In Victor, Baldwin has created the ultimate unreliable narrator. Everyone in Victor’s life — his twenty-five year-old, burlesque-loving girlfriend, his eighty-six year-old, gin-swigging aunt, his womanizing best friend, even his zany goddaughter — knows more about him than he does. Not only is he clueless about himself, he is tone deaf to other people’s motivations and feelings. As one character puts it, he suffers from Alzheimer’s of the emotions. His life is spent swimming and writing grants. Research, he complains, is like farm-league baseball where most of the work involves keeping a decent team together and raising money for new uniforms. For Victor, the thrill of scientific discovery belongs to the past.

It’s that very past that is coming back to haunt him, though. Just before her death in a car accident on the island, his wife, Sara, insisted that Victor go with her to see a therapist and try to save their failing marriage. The therapist suggested they each describe on five separate index cards five changes of direction in their relationship. Victor refused to do this but Sara did, except instead of five cards, it took her fifty-four. Victor has discovered these cards, and as he reads them, he begins to see their marriage from her point of view.

Sara was an artist when she and Victor met in 1971, and she pursued a career as a writer while Victor’s life was spent in his lab. She often felt emotionally abandoned; they had no children. And though Victor showed interest in her writing, she always felt he considered her work less important than his. But then she hit the jackpot. Her play Woman Turns Forty was hailed as a “feminist triumph” and made her famous. Later, her screenplay, The Hook-Up, made her rich as well. But their marriage, from Sara’s point of view, was falling apart. “As soon as we begin talking,” she tells him at one point, “we’re standing in separate rooms.” She goes to Los Angeles to work on a new screenplay; he buys a ticket to join her but never goes. She returns, hoping they can start again, but dies a few weeks later.

Crucially, as Victor reads the index cards, filled with descriptions of the slights and insults that constitute the jetsam of a long marriage, he realizes that he has little or no memory of them, or of that fateful moment when his comment to Sara, “You lost me there,” had far more significance than he knew.

Meanwhile, Victor’s actual life is getting the best of him. He drinks too much, his girlfriend dumps him, he does some very silly things, which on an island like Mount Desert do not go unnoticed. In short, the more he discovers about the past, the less he can cope with the present. Yet he must cope, and seeing him try is one of the delights of this excellent novel, which while illuminating the tragedy of grief and loss, never loses sight of the comedy inherent in trying to make sense of it all.