Jessica's visit to her cousin Abby turns sour when their host, Denton Langley, takes a fatal fall from his horse. Abby, the horse trainer on the farm, is certain that the horse was drugged and that Denton was murdered. Soon after, Langley's three children - Spencer, Trish, and Morgana - all assemble to meet with Langley's attorney, Mr. Boswell, to have the will read. Langley opted to make a video tape of his will, and so, on screen before his children, he leaves his entire estate to his faithful dog Teddy.
Langley's children are naturally upset, and they begin looking for ways to get rid of Teddy. Someone gives Teddy a drug to make him aggressive, and the neighbor, Mr. Potts, accuses Teddy of biting him. Jessica and Abby go to talk to Mr. Boswell, hoping to find out more about Potts. While they are at his office, Mr. Boswell receives a call from his broker, and after promising to send a check, confesses to the ladies that he lost a lot of money in the market on a stock that Spencer told him about.
That night, the security guard sees Trish's car pull up to the gate. When she gets out of the car, she is stumbling badly, and the guard comments that she is "drunk again". After he opens the gate, he sees her fall down by the gate, so he goes out to check on her, leaving Teddy in the security room alone. When he gets outside, he finds the gate is closing on Trish's head. He runs toward her but arrives too late, and she is killed. Teddy's pawprint is found on the button that closed the gate, and he is accused of murder.
Meanwhile, the superstitious Morgana, is telling her tale of seeing Trish's spirit arise and leave her body. Of course, everyone dismisses it as the ravings of a crazy woman.
Jessica wanders outside to the gate and talks to Will, one of the officers. She helps him to fold up Trish's jacket, and in doing so, notices that the arm seams are split, while the rest of the jacket appears to be new. She then continues to poke around, but eventually heads back to the house, where she finds Abby in the kitchen.
Mr. Boswell soon comes in and Jessica notices a grease stain on his pants. Boswell explains that he had a flat on the way to the house, and he must have gotten some grease on himelf then.
Jessica formulates a theory wherein the murderer drove Trish home in her own car, purposely swerving to appear to be driving drunk. The killer then put on Trish's coat, walked to the gate, and fell down. When the guard came out to help, the murderer was able to get up and put the drunken Trish back in his or her place. The killer then used the intercom to make a noise that served as a signal to Teddy to push the button that would close the gate.The sheriff finds a whistle by the driveway that belongs to Abby, so he arrests her
and Teddy for murder.
Boswell gives Jessica a ride back to the Langley home, but she asks to be dropped
off a half mile from the house. When Will, the officer she met earlier in the
episode, comes by, she tells him she is looking for a bicycle clip. Later, she
rides out to Mr. Potts' farm, where she finds Mr. Potts using a chainsaw. She
sees the bandage he had been wearing to cover the spot where he claimed Teddy bit
him, and she sees that his arm is fine. She takes the bandage and is about to
leave, but Spencer discovers her. Potts wants to kill Jessica, but she says that she knows who killed Trish, and that Potts' and Spencer's little scheme to break the will would hardly be noticed once she revealed the killer's identity.
Everyone gathers at the courthouse. Jessica demonstrates that Abby's whistle is an ultrasonic whistle and would not have been audible through the loudspeaker. Then she turns to Boswell. She said that although he did not expect to inherit, he was in debt and desperately needed he money that would result from having a long battle over the will. She then shows him the bicycle clip that she found and says that it fell off his bike, making his pants rub against the chain. This resulted in the grease mark that she saw on his pants. Boswell protests that he got that changing a tire, but Jessica tells him she saw his tire tracks and all of the tires were evenly worn. If there was a spare on the car, she would have seen one tire leaving deeper impressions.
She then tells Will to give Teddy the signal through the intercom. Teddy pushes the gate button, then runs to Boswell, expecting a reward. Boswell breaks down and confesses.
Teddy goes to live with a neighbor and Abby makes plans to leave the farm and go home to England.