From the announcement:
Fantasy Flight games is proud to announce Mountains of Madness, the second expansion for Eldritch Horror.
Inspired by H. P. Lovecraft’s novella about a Miskatonic University expedition that awoke ancient and deadly creatures, Mountains of Madness opens up to investigators the frozen expanses of Antarctica and releases horrors that have hibernated in the ice for eons. You may find in Antarctica solutions to many perplexing mysteries, but you will also encounter there profoundly disturbing sights and nightmarish new monsters. This expansion features a side board depicting locations throughout Antarctica, from the Miskatonic Outpost to the City of the Elder Things, where numerous and terrifying encounters await you. Two new Ancient Ones, including the very Elder Things that once dominated earth, threaten the end of humanity. Eight more investigators contribute their diverse skills and specialties to the struggle against the Ancient Ones. With their help you may be able to prevent the reawakened Elder Things from rising… or you may fall victim to the horror.