The Rape of the Lock opens with a brief letter from Pope to the poem's real-life subject, Arabella ("Belle") Fermor. In the letter, he explains why he wrote the poem in the first place, the circumstances that led him to publish it, and why he dedicates it to Arabella.
With Canto I, the official story begins. Here we meet Belinda, the poem's beautiful, rich, young society heroine, cuddled up with her dog in her sumptuous bedroom, just barely awake in the late morning/early afternoon. She's been having a sexy dream in which a handsome, well-dressed young man whispers sweet nothings into her ear. We're off to a rather pleasant start.
We learn that the dream has come from the sylph, Ariel, the airy spirit who watches over her. In the dream, Ariel explains the entire spirit-world of the poem, and introduces the sylphs and gnomes who will play important roles in the action later on. Belinda wakes up fully and rings for her maid, who helps her get dressed and put on her makeup for the day. Invisible to the humans, Belinda's army of attendant sylphs help with her face, hair, and outfit. As Canto II opens, a resplendent Belinda is in a barge, sailing down the River Thames on her way to a fancy party at Hampton Court, one of the country residences of the royal family. We learn here that her hairstyle features two curling locks that hang down the back of her neck. Ariel the sylph makes a speech to all of the other sylphs, telling them he's had a premonition that something terrible is about to happen, and that they should all be on their guard during the party.
The "something terrible" happens in Canto III, which finds Belinda at the party with all of her friends, sipping coffee (a novelty refreshment in the early 1700s, believe it or not) and playing a card game called Ombre, which is very similar to Hearts. The card game itself is described as a metaphorical battle between Belinda and her opponent, the Baron, who unbeknownst to Belinda is also scheming to steal one of her two locks of hair. After Belinda wins the game, the Baron borrows a pair of scissors from her frenemy, Clarissa. He sneaks up behind her and, despite all of the efforts of Ariel and the Sylphs, snips off the lock.
Canto IV opens with Belinda having a complete hysterical fit about the theft. Pope gives her rage a supernatural source, telling us that Umbriel, a resentful gnome, goes down to the underworld to pick up a bag full of tears, sobs, and anger, which he then empties over Belinda's head.
After this, there's no way that Belinda will laugh off the Baron's prank, even though Canto V begins with Clarissa trying to tell her to be a good sport about it. Belinda ignores this advice, and starts a fight between herself and her friends, and the Baron and his friends. It's more of a battle of insults and mean looks than a physical throwdown, but a ton of social damage gets done all the same.
Just when it looks like Belinda's side is winning, we discover that the lock of hair itself has gone missing. Has all of the drama been for nothing? Nope. The poem concludes with the poet himself claiming the overall victory, as he has written this beautiful poem commemorating the loss of the lock—and his own poetry chops—for all eternity. Poetry and Alexander Pope, rather than vanity and petty quarrelling, win in the end.