The Key in Animal Hospital: Ratthew and the Vault

If a small black rat has been visiting your check-in window, you are already partway through the most important item quest in Animal Hospital (Anomaly). Here is where the key comes from, what it opens, and what happens with each choice.

Where the key comes from

Ratthew is a recurring character who first appears somewhere between shifts 2 and 6. He is never an anomaly and can always be allowed in. Across his visits he warms up to you: he reveals his name on the second encounter, admits on a later visit that people wrongly treat him like an anomaly, and eventually tells you he must go into hiding because the Animal Corporation is after him.

Before disappearing, Ratthew speaks with you inside the Reception Office. He reveals that he had a twin sister, Rattina, who worked for the Animal Corporation and vanished without a trace — he has been searching for her ever since. He then hands you a key along with a note reading “Took this key from the doc…” (the “doc” being Dr. Harlow, from whom he stole it). After this conversation, Ratthew leaves the hospital permanently — though he later resurfaces at Liz’s house with a videotape recorded inside Animal Corp’s vents.

The choice: use it or hand it over

The key gives you two options:

1. Give it to Dr. Harlow. The key can simply be returned to its original owner.
2. Use it on the Vault. In Room 5 of the Medical Wing, take down the cat poster on the wall. Behind it is a hidden Vault that Ratthew’s key unlocks.

Opening the Vault also pays out: the Journal’s “Ratthew Secret” entry rewards 5 Animal Coins for opening the vault behind the Room 5 poster. His other Journal entries — 5 coins for learning his name, 10 for the final office talk — are listed in the Journal guide.

What is inside the Vault

The Vault contains three things:

• A suitcase with “TOP SECRET” written on it in red
• A photo of Rattina, Ratthew’s missing sister
• A note reading: “The experiment was a success, the ‘Shadow’ now sees everything…”

Together with Ratthew’s story, the contents tie Rattina directly to the Animal Corporation’s experiments — the same experiments other characters hint are the source of the anomalies roaming your hospital.

The Stalker will burn the photo

One documented interaction to know before you grab that photo: if you pick up Rattina’s photo and get close to the Stalker while it is lurking at the Reception Office, the photo disappears and the message “the photo burns in your hands” appears. If you want to keep the photo intact, do not carry it toward the reception area while the Stalker is registered there.

Quick answers

Can you miss the key? Ratthew only hands it over at the end of his encounter chain, after he has left the check-in office for his final Reception Office chat — so you need to keep letting him in across his visits. Rejecting or ignoring him means never reaching that conversation.

Is this the same as the Golden Key? No — the wiki documents a separate Golden Key item; this guide covers the vault key from Ratthew’s storyline specifically.

Does the Vault affect gameplay? Its contents are story items. The vault is lore-focused content — part of why the game’s “ending” is really its questlines, as covered in the shifts and ending guide. What the suitcase actually holds is not documented; the meaning of the “Shadow” experiment is left to the lore.

If you are still working toward shift 6 and have not met Ratthew yet, keep your check-ins clean and your sanity topped up — the beginner guide will get you there.