It had attachments designed to open any lock and untie any knot, even if they have been protected against the Unlocking Charm or similar spells. To use the device to open a locked door, one inserted its blade into the crack between door and door frame, then slide it up and down. However, there are some doors that cannot be opened by this knife, such as the door to the Love Chamber in the Department of Mysteries. That particular lock caused the blade to melt.
1994-1995 school year
During the Second Task of the Triwizard Tournament, Harry was required to free a hostage bound to a statue in the Merpeople village in Black Lake, and he regretted not bringing Sirius' knife with him. He was forced to make do with a sharp rock.
1995-1996 school year
On two occasions during his fifth year, Harry used the knife to break into Dolores Umbridge's office, as all other fireplaces but hers were being watched, and he desperately wanted to contact Sirius Black via the Floo Network on both occassions.
In the Department of Mysteries, Harry tried to use the knife to open the door to the Love Chamber, but the blade melted. It is not known whether he ever managed to have it repaired, although it may have had multiple blades among its "attachments." In any case, following the failed attempt to unlock the door, he placed the "now-useless" handle of the knife in his pocket.
Notes and references
- ↑ 1.0 1.1 Harry Potter and the Goblet of Fire, Chapter 23 (The Yule Ball)
- ↑ 2.0 2.1 Harry Potter and the Order of the Phoenix, Chapter 29 (Careers Advice)
- ↑ 3.0 3.1 Harry Potter and the Order of the Phoenix, Chapter 34 (The Department of Mysteries)
- ↑ Harry Potter and the Goblet of Fire, Chapter 26 (The Second Task)
- ↑ Harry Potter and the Order of the Phoenix, Chapter 32 (Out of the Fire)