The Monster (Boris Karloff)’s Timeline and Summary

Henry Frankenstein and his assistant Fritz build a monster out of dead body parts and reanimate it using electricity.
The monster's kept locked up; Fritz torments it with fire.
Bad move Fritz; the monster kills his tormentor.
Frankenstein's upset; he and his teacher Dr. Waldman drug the monster unconscious.
Frankenstein leaves his remote lab to prepare for his wedding; Waldman decides to vivisect the monster and then destroy it.
The monster strangles Waldman before Waldman can kill it.
Then the monster heads out for an excursion. It plays with a little girl, and then accidentally kills her.
The villagers are enraged, and organize a search party to kill the monster.
Frankenstein helps lead the search party, and ends up confronting the monster.
The monster captures him and takes him to a windmill.
The windmill's surrounded by villagers. The monster and Frankenstein struggle, and Frankenstein falls from the windmill.
The villagers burn the windmill, killing the monster.
Poor monster (but don't cry—he'll be back in Bride of Frankenstein).