The old Riddle House in the village of Little Hangleton has been the subject of rumors for 50 years. 50 years ago, a maid found the three members of the Riddle family dead. The villagers were initially shocked and then thrilled that Frank Bryce, the Riddles' gardener, was arrested. However, the report about the Riddles' bodies couldn't find a cause of death--it looked as though they'd died of fright. The police released Frank, who returned to the Riddle House and tended the grounds for the next owners.
Pay attention to the way in which the villagers so quickly change their thinking about Frank Bryce to believe he killed his employers. This allows the reader to see how people can easily latch onto an idea if it seems attractive, regardless of whether or not it's actually probable. In doing so, the novel shows that it's easy to sidestep critical thinking in favor of going with what's easy.
In the present, the owner of the Riddle House doesn't live there, though he still pays Frank to maintain the grounds. Now that he's almost 80, Frank struggles to keep up, and the cruel local boys make things worse by breaking windows and riding on the lawns. One night, Frank wakes up when his bad leg starts hurting. As he fills his hot water bottle, he notices a light on at the house and figures that the local boys broke in and lit a fire. He dresses quickly and heads up to the house.
The local boys that torment Frank introduce the reader to a starting point of coming of age: these boys feel entitled to treat Frank like this because they selfishly don't believe that he's worthy of respect or empathy. In turn, Frank doesn't feel compelled to empathize with the boys either, hence why he immediately blames them.
Frank climbs the stairs and finds the intruders in a room at the end of the hallway. There's a fire in the grate and seeing this, Frank stops to listen. A scared-sounding man, Wormtail, offers something to a second man (Voldemort), whom Frank can't see but whose voice sounds cold and high-pitched. The two men puzzle Frank by talking about the Quidditch World Cup, Muggles, and the Ministry of Magic. Frank believes he's listening to criminals or spies.
A reader familiar with the Harry Potter series is led to believe that the second voice is Voldemort. This raises the question of whether Voldemort now actually has a body. Frank's reasoning about what he's listening to shows that he desperately wants to make things make sense when he doesn't understand them.
Wormtail suggests that they should do "it" without Harry Potter, but Voldemort accuses Wormtail of attempting to desert him and insists that he won't use anyone else. Wormtail notes that Bertha Jorkins's disappearance will soon raise suspicions, and the two men discuss killing one more person before killing Harry Potter. Chilled and sweaty, Frank realizes that Voldemort is speaking about killing people with amusement. He knows he needs to go to the police but as he turns to go, Voldemort says that he hears Nagini coming. Frozen with fear, Frank watches a massive snake slither past and into the room.
Frank's decision to call for the police shows that he knows how to call on his community to protect other people as needed. He understands that it's his responsibility as an individual to do what he can to protect others, even if he doesn't know Harry Potter or Bertha Jorkins. This illustrates that even in the case of this man the reader doesn't really know, everyone has the power to choose whether to help others or go along with evil.
Frank listens to Voldemort hiss and spit, but thinks it's impossible that he's talking to the snake. Voldemort tells Wormtail that Nagini has news: there's a Muggle in the hallway. Wormtail shows Frank into the room. Frank can't see Voldemort sitting in the armchair, but draws up his courage and threatens to go to the police. He also says that his wife knows he's here. Voldemort says—correctly—that Frank has no wife, and Frank challenges Voldemort to face him like a man. Wormtail turns the chair around but when Frank sees the being sitting in it, he screams. He dies in a flash of green light, while Harry Potter wakes up hundreds of miles away.
The fact that all of this wakes Harry up calls into question whether or not this chapter is a dream. It will be possible for Harry to interpret it either way, which will give him the opportunity to begin to parse the differences between truth and imagination as well as learn to trust himself and his own interpretation of things. Voldemort's cruelty in killing Frank shows he has little regard for others, even though it's unlikely Muggle police would have had any effect on Voldemort.