Among the items on his "Doomsday List" is Isobel Le Fournier, who, we learn, was Daguerre's first (and only) love. Much of the novel is given over to flashbacks of their early days together and the circumstances of their parting, as well as his attempt to find her again before it's too late.
While there were few surprises about the trajectory this book took, I liked the descriptions of Daguerre's photographic experiments and processes, and as characters he and Isobel worked nicely together. The descriptions of the difficult times in France during the late 1840s were well done, and Smith can turn a good phrase.