What actually happens
Brains are sold separately
In a village in the Bavarian Alps, Henry Frankenstein and his hunchbacked assistant Fritz put together a human body out of parts from fresh graves and executed criminals. Henry wants to bring it to life with electricity, and he still needs a brain. His old teacher, Doctor Waldman, shows his class a healthy brain and a damaged one, and Henry sends Fritz to steal the healthy one. Fritz accidentally damages it, so Henry ends up with the criminal's brain. Meanwhile Henry's fiancée Elizabeth and their friend Victor worry about how he has shut himself away. They talk to Waldman, and all three arrive at the tower as Henry finishes his preparations during a storm. The table is raised toward the roof, the lightning hits, and the creature moves. Henry proclaims that he now knows what it is like to be God.
Reading this instead of watching it is the correct decision. Scaredy Cat makes that decision automatic, for free.
The torch is a bad idea
The Monster is childlike and seems innocent. Henry welcomes it into the laboratory and asks it to sit, and when he opens the roof, the Monster reaches toward the sunlight. Then Fritz walks in with a flaming torch, and the Monster is frightened. Henry and Waldman read the fear as an attack, and they chain the Monster in the dungeon, where Fritz keeps tormenting it with the torch. Henry and Waldman hear Fritz screaming and find that the Monster has hanged him. It lunges at them, and they lock it in. Waldman injects a strong drug into its back, and the Monster is knocked out.
The flowers run out
Henry collapses from exhaustion, and Elizabeth and his father take him home, where he recovers and gets ready for his wedding. Waldman stays behind to examine the Monster and starts to prepare to vivisect it, but the Monster wakes up and strangles him. It escapes the tower and wanders the countryside until it meets Maria, a farmer's daughter. She invites it to play a game of tossing flowers onto a lake, and the Monster enjoys it. This is the scene people dread most, and it happens around the middle. When the flowers run out, the Monster throws Maria into the lake as well, and she drowns. The film frames it as an accident, since the Monster did not mean to drown her.
A wedding with a mob in it
The wedding is ready, and Henry is happy with Elizabeth, and they will marry as soon as Waldman arrives. Victor runs in to say that Waldman has been found strangled, and Henry guesses it was the Monster. The Monster enters Elizabeth's room and she screams, and she is found in shock, then unconscious. The Monster escapes again. Maria's father arrives carrying his drowned daughter and claims she was murdered, and the villagers put together a lynch mob. During the search, the Monster attacks Henry, knocks him out and carries him up an old windmill. The villagers see it dragging Henry to the top, and it throws him down, though the windmill blades break his fall. Villagers carry him home, and the rest of the mob sets the windmill on fire with the Monster trapped inside.
The ending, explained
The windmill burns with the Monster trapped inside. Henry survives the fall because the blades slow him, and the villagers take him home. The last scene is at Castle Frankenstein, where Henry's father toasts his recovered son's wedding and wishes the couple a grandchild. Waldman, Fritz and Maria are dead, and the Monster is left in the burning windmill.
The post-credits ruling
Nobody has confirmed whether there is a scene after the credits, so staying to check is your call.
✓ Spoiled safelyDog status: fine, no dog dies.
Questions people ask at 1am
Is Frankenstein scary?
Barely. Frankenstein is a 2.5 out of 10: an old monster story with a few jump scares and low dread, and its saddest scene happens at a lake.
How does Frankenstein end?
The villagers burn the windmill with the Monster inside. Henry survives and his father celebrates the wedding with a toast to a future grandchild.
Does the dog die in Frankenstein?
No dog dies in Frankenstein.
Is there a post-credits scene in Frankenstein?
Nobody has confirmed either way, so Frankenstein may or may not have one.
Why does the Monster in Frankenstein turn violent?
In Frankenstein the Monster starts out childlike. It is frightened by Fritz's torch, chained in a dungeon and tormented, and then it hangs Fritz. Later it strangles Waldman and drowns Maria without meaning to.