As the heroine of this popular prime-time series, Jessica Fletcher (Angela Lansbury) is constantly gathering material for her next best-seller, using her know-how as a mystery writer to solve a slew of real-life murders. In the show's third season, Jessica stakes out a circus to track down a long-lost relative; looks into the death of a fast-food advertising executive; and offers assistance to Thomas Magnum (Tom Selleck's "Magnum, P.I." persona).