Harry Potter has got a knife that can open any locked door from his godfather Sirius Black. This knife gets destroyed in Order of the Phoenix chapter 34.

When did Sirius acquire the knife? Presumably he didn't have it with him in Azkaban, because it's unlikely that they let him keep such an item in prison. Did he already have that knife before he was taken to prison, but has hidden it somewhere outside, such as in the Black Manor? Did he have it when he broke into the Gryffindor tower in Prisoner of Azkaban chapter 13, or before that, when he slashed the Fat Lady's portrait?

Also, how did Sirius acquire his knife? Is this an ordinary item you can just buy in a shop (if you're not a fugitive searched by the Ministry of Magic that is)? Is it rare and valuable? Do we know its story?

  • I don't believe it has any back-story other than what's in the books. Sirius acquired it (somehow) and gave it to Harry who ended up ruining it.
    – Valorum
    Aug 2, 2016 at 22:05
  • Probably stored in a safe in Grimmauld 12
    – bleh
    Aug 2, 2016 at 22:59
  • " Presumably he didn't have it with him in Azkaban, because it's unlikely that they let him keep such an item in prison. " - and, presumably, he wouldn't have stuck around the prison if he had such a tool at his disposal. :D Aug 3, 2016 at 16:32

1 Answer 1


We don't really know

Not much is said about the nature or origin of the penknife. The main description of it is:

[...]Sirius, a handy penknife with attachments to unlock any lock and undo any knot[...]

Harry Potter and the Goblet of Fire

We know that it probably can get past enchantments designed to counter Alohomora:

“Christmas before last Sirius gave me a knife that’ll open any lock,” said Harry. “So even if she’s bewitched the door so Alohomora won’t work, which I bet she has —”

Harry Potter and the Order of the Phoenix

However, it certainly is not infallible:

“Sirius’s knife!” said Harry, and he pulled it out from inside his robes and slid it into the crack between the door and the wall. The others all watched eagerly as he ran it from top to bottom, withdrew it, and then flung his shoulder again at the door. It remained as firmly shut as ever. What was more, when Harry looked down at the knife, he saw that the blade had melted.

Harry Potter and the Order of the Phoenix

As such, I think there is no reason to assume that it is not simply a readily available magical item; in other words, the sort of thing that someone with enough money could buy in Diagon Alley.

To the best of my knowledge, we have no evidence as to whether Sirius had possessed it before he was sent to Azkaban (and perhaps used it in his escapades), or whether he purchased it after escaping.

  • I'm reasonably sure that you can't buy burglary tools in Diagon Alley. Maybe Nocturn Alley...
    – Valorum
    Aug 3, 2016 at 21:02
  • @Valorum - Perhaps so. ;)
    – Adamant
    Aug 3, 2016 at 21:03
  • @valorum Peruvian Instant Darkness Powder is sold by Weasley's Wizard Wheezes. I can see zonko and the weasleys also selling an all-opening knife
    – user68762
    Aug 5, 2016 at 10:54
  • Instant darkness powder can be used for japes and merriment. I see no reasonable use for a lock-picking kit other than for picking locks.
    – Valorum
    Aug 5, 2016 at 11:40
  • @valorum lockpicking =/= burglary. Maybe they thought it'd be nice for pranks. After all they sell love potions and smuggle them into Hogwarts in shampoo containers. a handy knife isn't much worse.
    – user68762
    Aug 5, 2016 at 18:01

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