Luigi's Mansion: Dark Moon -- Haunted Towers - B-5 Doggone Key

Gadd says the Polterpup that took the special key is still in the Haunted Towers, but runs room to room, so Gadd can't pinpoint a location. The Parascope found that the Polterpup left paw prints starting in the Courtyard, so we'll be able to follow it. The Dark Light will make the paw prints visible.

Entrance
We land in the Entrance and we can see the Polterpup just beyond the gate. The tree on the left has a gold frog.

Courtyard
The Polterpup swallows the key and goes into the Hydro Generator room.

Hydro Generator
Use the Dark Light to find the paw prints and follow them to find where the Polterpup went through the wall.

Garden
Eventually, the trail will lead you here. The Polterpup will turn on the lawnmower and leave. Then, three Sneakers will appear.

Tool Shed
When you return here, you'll notice most of the furniture missing. Restore it all to make French Boodle appear. Spin the fountain to go to the Toolshed Stairs.

Toolshed Stairs
The Polterpup was napping on the bed, but runs upstairs. There's a Creeper at the bottom of the stairs. The Polterpup will disappear on the third floor. Go through the Botany Lab and Seedling Laboratory. It will then go to the fourth floor. Check the drawer at the bottom of the stairs between the third and fourth floor for a Gold Greenie.

Conservatory
The Polterpup is here and the organ is missing. Restore the organ and play it to make the Polterpup appear. It runs behind the organ. If you try to follow it, a Creeper will trap you, allowing the Polterpup to escape. If you try to leave, the doors will be blocked and a Gobber and some Greenies will appear. Go to the West Bathroom once you're done.

West Bathroom
The Polterpup will hide when you appear. Restore the toilet for money. The Polterpup is hiding in what I'm guessing is the bidet. It will run into the West Bedroom. Deal with the Creepers in the West Hall and move on.

West Bedroom
There's a Creeper on the ceiling. The Polterpup is hiding in one of the beds, so follow the paw prints. Once you find it, you can finally vacuum it up. It has 50 HP. The key will appear when you defeat it. What a wild goose chase. Gadd thinks the Polterpup wanted someone to play with. He brings us back to the Bunker.

Clear Time: 14:44
Ghosts Captured: 16
Health Lost: 72
Treasure: 872
Gold Rank

When you have 20,000 G, the Poltergust 5000 will be upgraded to catch ghosts faster. The Polterpup was not sent to the Vault and escapes. We recovered the key, but the Polterpup chewed it up and drooled on it. Toad gets the special task of cleaning it before Gadd repairs it. Gadd can now use the two Dark Moon pieces we have to locate the third.