-When you first find Meryl and she runs into the elevator, avoid chasing after her. Instead, run into the door to the left of the elevator. You will only have to fight Raven in the cold room next to the furnace room and Sniper Wolf in the cleared snowy area.
-While in the first area, walk over to the sleeping guard. Flip him and crawl into the vent. You will see rats in the vent. Chase them and they will lead you directly to area 2.