The Furnace is shrinking Pluto. It's very hot.
Mum says you can't approach the Furnace until you have heat protection. If you need heat protection, use these hints.
You need extra muscle to deal with the Furnace. Who is close by and has a vested interest in shutting the Furnace down?
Walk to the right and find a Plutoon. Interact with them.
Interact with the Furnace again.