What we know so....far
Lara Croft and the Temple of Osiris takes place in Egypt, where Lara has to work with a rival treasure hunter, Carter Bell, as well as imprisoned gods Horus and Isis, to defeat Set, an evil god. The goal of the game is to stop Set by acquiring all of the fragments of Osiris before he enslaves all of mankind. The game also marks a return to co-op play, though it will allow for up to four players to solve puzzles, avoid death traps, and collect artifacts.
Source: True achievements