1) Government conspiracy theory: There are rumors that Nazis had a secret base in the Arctic near Lake Vostok (http://thelede.blogs.nytimes.com/2012/02/08/world-war-ii-rum...). This one cuts between today and 1945 when two German submarines were seen in Argentina. Then, US had Operation Highjump (Operation Highjump) and, later in 1958 a few nuclear tests. And now the Russians are so anxious to get to the Lake. Why the focus on this area? It is revealed that ...
2) SF Aliens: The probe sent to Vostok inadvertently triggers and alien auto-surveillance device that is protecting a ship that crashed into Antarctica millions of years ago. After considerable loss of life, the ship is reached and the aliens are rejuvenated with terrible results. Difference between this and The Thing would be the awesome underwater shots.
3) Magical Aliens: Three words: Mountains of Madness (http://en.wikipedia.org/wiki/Mountains_of_madness). People laughed at Lovecraft but maybe he was much more well-informed than we assumed. The mountains mentioned are, of course, real: http://news.nationalgeographic.com/news/2010/01/photogalleri.... The Russian expedition is all fun and games until a weird guy (who double majored in ancient languages) points out that in the extinct Omaguaca language of Argentina the area around Vostok is called "Raulya", which is evidently where Cthulhu is sleeping. The greedy Russians wake him up (similar to what happened in Moria) and chaos ensues.
I would be leaning toward a mixture of (3) and (1).