A generation ago, Angela Lansbury spent 264 television episodes as Jessica Fletcher, an Agatha Christie-style detective who solved murders for the most part right in her own backyard, the sleepy rural town of Cabot Cove, Me. Two observations occurred to me: why would anyone hang out with Jessica once you realize that wherever she is someone gets murdered? And what’s the matter with Cabot Cove, a little fishing village that has a violent crime wave commensurate with Chicago?