TL;DR

Millie is obsessed with death and literature. She meets someone with the same interests until she catches him kissing another girl. At Christmas, she sneaks away to hide from the family party, and finds a Funtime Freddy in her Grandpa’s workshop. She falls asleep inside of him and wakes up to his booming voice as he looks down on her. Freddy tells her he will kill her, but she has to pick how. Millie ends up picking decapitation, hoping the blade will miss, and the story ends with the blade slicing through the cavity.

Full Summary

Millie is a high-school goth girl who's parents left for a job opportunity in Saudi Arabia. Millie could go with them and be homeschooled or she could stay at her Grandpa's house and go to the local high-school. She chooses the latter, and decides to live with her Grandpa who was a collector of old licence plates, hubcaps, baseball bats, etc. Grandpa, however, is concerned about her lifestyle. She likes to make her face look more pale to which Grandpa tells her she needs more iron in her diet and some more sun. This angers Millie, who storms up to her room to read and write poetry about Death. Grandpa tries hard to regain her respect by coming up with cookies and although she accepts and enjoys them, it doesn't change her mood against Grandpa.

At school, Millie gets bullied for her make-up, being called 'Dracula's daughter'. Additionally, her parents were known for starting ambitious projects and then abandoning them, so she didn't know which insult to her was worse. As she sits in the school cafeteria reading and thinking about her ex-best friend, Hannah, a new boy named Dylan sits with her. They share interests in literature and attitudes toward school, so they decide to meet for lunch again the next day. This was a win for Millie - so much so, she started talking to her Grandpa and eating her food. They bond over 'Annabel Lee' by Edgar Allen Poe, to which Grandpa talks about his wife who passed away when she was only forty. Millie feels sorry for Grandpa and soon leaves to do her homework.

In the school cafeteria the next day, Dylan meets Millie once again and hands her 'The Call of Cthulhu and Other Stories' by H.P. Lovecraft, which she reads through after dinner. After the day is over, she writes another poem, but instead of it being focussed on Death, she writes about love. On the weekend, she goes to the public library and finds Dylan in there. He gives her another story to read and then they go next-door, to You and Me Coffee and Tea. While inside, Millie tells Dylan a secret she has never told anyone before - she would like to become a librarian one day.

One day when Millie gets home from school, her Grandpa asks her if she'd like to go to the school's holiday bazaar. Millie's Grandpa use to be a teacher at the school, so he would be occupied while Millie could hang out with Dylan. She agrees to go, and searches for Dylan when she gets there. She finds him behind a booth selling ornaments, holding hands with Brooke Harrison - a blandly pretty blonde girl. In jealousy, Millie has a breakdown and demands Grandpa to go home. On the next school-day, Dylan comes to sit across from Millie, to which she asks how he can just sit across from her like that. He explains that Brooke is his girlfriend and how he never meant to mislead Millie. After an argument about judging a book by its cover, Dylan ends the conversation by leaving the table.

Millie decides not to celebrate Christmas just because it's 'what society tells us to do', and her Grandpa feels concerned. They argue over Millie's attitude, and both storm out of the room in rage. On Christmas Eve, Grandpa holds a Christmas party, inviting Millie's Aunt Sheri, Uncle Rob and cousins Cameron and Hayden. When Uncle Rob asks if she's going to a funeral, Millie's Grandpa tells them that she is not celebrating Christmas, which confuses the children. She announces that she's going for a walk, and takes a walk around the block before hiding from the party in the workshop. When she turns on the light, she sees all of Grandpa's collectibles, including a deactivated mechanical bear, Funtime Freddy. She climbs inside and falls asleep.

When she wakes up, she hears a silly booming voice, wondering where it's coming from. She looks up to see a pair of eyes, looking down on her. Funtime Freddy tells her that he's going to kill her, but she gets to decide how she will be killed. He gives some information on the options of dehydration, starvation, hypothermia, impalement, electrocution, boiling and decapitation. Millie screams but the animatronic's metal dampens the sound completely. Freddy makes her feel terrible about herself, and she tells herself that if she makes it out alive, she'll be more appreciative of her family and the world. Attempting to escape, she takes off the silver cuff bracelet on her wrist in hope to try and pry the door open. She picks decapitation, thinking she could dodge the blade and escape just in time. The blade slices through the chamber.

Grandpa finishes the roast dinner and the family are concerned about where Millie is, but they start to eat without her, arguing that she'll come back when she's ready. After the meal, Grandpa goes into the kitchen to make hot chocolates and finally breaks down, calling Millie, but she left her phone at home. He goes back into the living room where the children are opening presents. Grandpa arranges all of Millie's presents in a pile so that they will be there when she gets back.

The 'Grandpa' Conspiracy (Debunked)

Before we knew Millie's fate from the final Stitchwraith Stinger, I had created this interesting conspiracy which is a fascinating way to look at this story as it stands alone.

How does Funtime Freddy know everything he knows? He could be possessed, but that doesn't fully explain it. Not only is he aware of death and the extensive history of punishments, but he also knows a lot about Millie and her family. This theory suggests there is actually an insider - somebody watching over Millie and reporting back to Funtime Freddy. The conspiracy is that Grandpa found the robot in the scrapyard and reprogrammed it to kill Millie (If this were true, it could parallel William Afton!) Grandpa is specifically called out as the 'weirdo' in the town - liking to collect all sorts of old items. Throughout the story he is fed up with Millie's lifestyle, where everything is about Death (literature, music, goth make-up, attitude...) and so when he gets the opportunity, he decides to give her the wish she has always been talking about. When Millie falls asleep in Funtime Freddy, her Grandpa does find her, but shuts the door and activates the robot.