Retrieving the Mysterious Box is the main goal of the "Find the Mysterious Box" quest, which is randomly offered to the player at port in London.
A peculiar scientist asks the explorer to bring him the box back, after the expedition. If player agrees to deliver, he will receive the Scientist's Map.
Digging in a spot marked on the map (by standing on marked hex and using a shovel) will allow party to loot the box.
Opening the Box[]
Instead of being brought back to the scientist, the mysterious box can be opened during expedition. If opened, the explorers can see that inside the box there is a dead cat. Suddenly, a small black spot appears and the void, a dark and impenetrable shadow, starts devouring everything in its path. If the expedition doesn't run away fast enough, they will be trapped by the void and die.
Trivia[]
This is a direct reference to the thought experiment Schrödinger's Cat.