When Shawn and Henry are invited to have Christmas dinner with Gus' parents, the yuletide cheer is interrupted by... murder. A neighbor is found dead and all the evidence points to Gus' dad as the culprit. Can Shawn and Gus work their usual magic when the case is so personal?
It's Christmastime and the Gusters have invited Shawn and Henry over for dinner, one of only a handful of such invitations ever extended to the Spencers since Bill and Winnie Guster have always thought of Shawn as a bad influence on their son. After their meal, during which Shawn tries to prove he's actually been a help to Gus over the years, the group goes caroling through the old neighborhood, starting with everyone's most hated neighbor - Old Man Fuller. But when they get up to the house, Shawn knocks on the front door, which swings open to reveal Fuller, hanging from the banister.
Lassiter and Juliet arrive to what looks like a suicide. Shawn notices a wound on Fuller's head and a stain on his shirt. Also, a broken teacup, a gourmet meal, and shows circled for that night in a TV guide. All of which, Shawn believes, point to murder instead of suicide. Plus a man of Fuller's age and condition could never have hoisted himself over the banister. Shawn is determined to solve the case to impress Gus' parents, so he has a "vision" Fuller was a victim of foul play, making the cops take a second look at the evidence, which confirms Shawn's suspicions.
Shawn, Gus and the Gusters arrive at the police station to give their statements. Lassiter tells them that weed killer was found in Fuller's system - weed killer that belongs to Bill. Bill admits to poisoning Fuller's plants in a long-standing dispute over the property line. Lassiter goes on to say that Fuller's head wound was caused by a hammer - a hammer that had Bill's fingerprints on it. Bill says Fuller took the hammer, along with several other tools, and never gave them back. Lastly, Lassiter says the rope used to hang Fuller came from Bill's boat. Bill, unfortunately, has no explanation for that one, and the cops are forced to arrest Gus' dad.
Back in the neighborhood, Shawn notices that Fuller's house is in a shocking state of disrepair, and realizes he probably not only had a feud with Bill, but the homeowner's association as well. He tracks down it's head, Carl Mitchell, who says Fuller was a constant thorn in his side. But he was also a constant supporter of the Mitchell Family, who founded the neighborhood a hundred years ago and are lobbying to have it declared a historical district. Fuller always refused to sell his house, preserving the original architecture of the neighborhood, and the Mitchells were his only friends. Mrs. Mitchell arrives and remembers them from when they were kids, reminding them she paid them $5 to mow the lawn years ago and they never completed the job. So she sets them to work in her yard, telling them to make sure they water the gardenias, which she's had longer than they've been alive. While in the yard, Shawn sees someone moving around in Fuller's house. They once again bail on mowing the Mitchell's yard and run over to catch the intruder, who turns out to be a realtor looking to list the house. She tells them she's been cold calling Fuller for years, trying to get him to sell through her. His house is the only property in the neighborhood with 360 degree unobstructed views and will sell for a fortune. Gus insists they have a new prime suspect. Shawn is hesitant but offers to have the cops look into her background and check the phone records. Lassiter and Juliet show up, having in fact found something suspicious in the phone records. But instead of implicating the realtor, they arrest Winnie instead, who made numerous calls and cash transfers to Fuller.