While visiting her nephew in New York, Jessica runs into a former student, Elizabeth Gordon, in town for a cosmetics convention. Visiting her apartment, Jessica finds Elizabeth murdered and her portrait defaced with lipstick.

A new themed diner opened just off the interstate in Cabot Cove, drawing the praise of the town's residents and the ire of a competing diner owner. However, when a visiting diner ends up dead and several other diners getting sick from apparently food poisoning, Seth and Jessica help Sheriff Tupper wade through a long list of suspects to find out what their motive was for the poisoning.