Taylor O'Brian takes small groups on wine country tours of romantic Sonoma County. Friends are everything in the tour business, so Taylor is happy to guide investors to the winery owned by her friend Tim Slade. But vintage turns to vinegar when an FDA inspector is found floating face down in one of Tim's vats of squished grapes. Tim is arrested on suspicion of murder, and Taylor and her friends rally to prove his innocence. But it's not an easy task, especially since the winery proprietor's acidic sense of humor tends to reap a harvest of sour grapes. Taylor's investigation is withering on the vine until she discovers that Tim's girlfriend, Mandy, is having an affair with a self-help guru. But before she has a chance to confront Mandy, Taylor finds Tim standing over the body of the dead guru.