Break-in of Gringotts Wizarding Bank (1998)

"…yeh'd be mad ter try an' rob it."

- Rubeus Hagrid on Gringotts

There was a break-in of Gringotts Wizarding Bank during the height of the Second Wizarding War carried out by Harry Potter, Hermione Granger, and Ron Weasley in order to steal one of Lord Voldemort’s Horcruxes from the vault of the Lestrange family. The trio was assisted by Griphook, a former employee of Gringotts, who agreed to help them in exchange for Godric Gryffindor's Sword, but double-crossed them. They acquired Helga Hufflepuff's Cup and flew a blind dragon out of the bank in what would become a famous escape.

Background
After escaping Malfoy Manor in the spring of 1998, Harry Potter, Ron Weasley, and Hermione Granger stayed at Shell Cottage for a time with Luna Lovegood, Dean Thomas, Mr. Ollivander, and Griphook. When Bellatrix Lestrange had interrogated and tortured Hermione with the Cruciatus Curse at Malfoy Manor, she revealed that there was something in her vault at Gringotts that was very valuable to Lord Voldemort. Harry and his friends deduced that this was another of Voldemort’s Horcruxes, and thus needed a way to get into the vault in order to steal it.

Bargain with Griphook
To this end, they bargained with Griphook, a former employee of Gringotts, to help them break in. He agreed to help them – in exchange for Godric Gryffindor's Sword. As Bill Weasley explained to Harry, goblins have different conceptions of ownership than wizards, considering the maker and not the buyer to be the true owner. Griphook also claimed that Godric Gryffindor had stolen the sword from goblin Ragnuk the First.

Harry reluctantly agreed to Griphook’s ultimatum, though he planned to only hand it over after he, Ron and Hermione had used it to destroy Horcruxes. Griphook was also suspicious of any wizard’s ability to keep his word, given the poor history between his people and wizards.

Disguise
Hermione then used a strand of Bellatrix’s hair, which had fallen onto her sweater back when she was being held at Malfoy Manor, to brew Polyjuice Potion and disguise herself as Bellatrix. She also transfigured various aspects of Ron’s appearance to disguise him as “Dragomir Despard”, a foreign wizard. Harry and Griphook hid under his Invisibility Cloak and the group headed to the bank.

At first, Hermione had difficulty imitating Bellatrix, as she was “too polite” to one person and then too rude to a wizard who Griphook revealed was Travers, another Death Eater. However, with a “magnificent imitation of Bellatrix's most contemptuous manner”, she managed to make Travers less suspicious. She and Ron were accompanied by Travers into Gringotts.

Getting In
"Gold, filthy gold! We cannot live without it, yet I confess I deplore the necessity of consorting with our long-fingered friends."

- Travers on the goblins of Gringotts

Once the group entered, guards used Probity Probes on them to detect any spells of concealment or magical items. Harry quickly used the Confundus Charm on the guards so that they let them through.

When they reached the counters, Travers presented his key and Hermione was asked to hand over her wand for identification. Griphook hissed in Harry’s ear that “they must have been warned there might be an imposter”. This indicates that the real Bellatrix must have warned Gringotts that someone using her wand – which Harry took in the escape and which Hermione was forced to use since her own had been taken by Snatchers – might try to get into her vault. Harry used the Imperius Curse on the goblins so that they would believe it was another wand. When Travers questioned how she could have gotten a new wand, Harry used the Imperius Curse on him as well.

The goblin Bogrod then led the group to the Lestrange family vault, and Harry sent away the others, including Travers. They took a cart there, and passed through the Thief's Downfall, which washes away all magical concealment, thus restoring Hermione and Ron’s true appearances. Suspecting that Gringotts was aware of a security breach, they hurried to the door, which was guarded by a half-blind dragon. With Bogrod with them, they were able to get past the dragon and into the vault.

Obtaining the Cup
Harry, Ron, Hermione and Griphook searched the treasure-filled room for either Helga Hufflepuff's Cup or an item that once belonged to Rowena Ravenclaw. For security, Geminio and Flagrante curses had been added to the treasure so that it would expand if touched and turned hot enough to burn the skin. As time went on, the treasure started to grow and the heat began to rise.

Eventually, they spotted Hufflepuff’s Cup. Hermione used Levicorpus on Harry to lift him closer to it. As she, Ron, Griphook became buried in burning treasure, Harry slipped Gryffindor’s Sword through the handle of the cup to pull it down. Griphook then seized the sword and fled, screaming that there were thieves as a crowd of armed goblins approached the vault.

Escape
Harry, Ron and Hermione all fired stunning spells at the oncoming goblins to hold them off. Harry then used a Revulsion Jinx to free the dragon from its chains, and the trio climbed on its back. The dragon began to breathe fire at the goblins and to fly through the corridor that was almost too narrow for it, while the goblins threw daggers at them.

Hermione used Defodio to enlarge the passageway for the dragon, and Harry and Ron copied her. Their combined efforts and the dragon’s violent thrashing let them break into the main hallway. As customers and employees fled, the dragon burst out of the doors into Diagon Alley, and launched itself into the sky.

Aftermath
Harry, Ron and Hermione eventually leapt off the dragon into a lake. Their break-in and escape from Gringotts would become infamous, as students from Hogwarts heard the news despite the school being under the Death Eaters' tyrannical control.

Although they had acquired an additional Horcrux, their break-in also exposed their plan to Lord Voldemort. Harry, through his connection to Voldemort, was witness to his fury that his secret had been discovered and his determination to check if all the other Horcruxes were safe. This vision also revealed that the final Horcrux was at Hogwarts. Thus, the trio planned to return to Hogwarts, setting the stage for the final battle of the Second Wizarding War.