Winston Churchill referred to his depression as "the black dog." This novel imagines if that was a real, literal dog. In 1967, on the eve of Churchill's retirement from Parliament and public life, a giant black dog (who goes by the name Mr. Chartwell or Black Pat) comes to stay with a quiet library clerk named Esther, who has a room to rent. This talking dog has a job to do that involves Churchill somehow.

The extended metaphor is funny but never really resonated with me as a way of envisioning the effect of depression on someone's mind. The wispy library clerk, described in terms of flyaway cardigans and stained work dresses, is the only character with whom I felt a connection. A connection with her, as well as another metaphor for depression the author keeps returning to: a wave of blackness, ebbing and flowing, while the swimmer tries to keep sight of a distant tiny light on the shore. Those were the highlights of the novel for me.

It's an odd book, and it didn't seem quite like "magical realism", more like allegory.