As Murder, She Wrote saunters through its sixth (of an eventual 12) season, star Angela Lansbury maintains her eternally buoyant and inquisitive air as Jessica Fletcher, professional writer and amateur sleuth. Though Jessica continued to investigate murders in her home town of Cabot Cove and elsewhere (in the worlds of high finance, opera, and voodoo, among other settings), this season began the practice of guest detective episodes, introduced by Jessica as either a story she wrote or a tale told by a frien…