Xolotl is a god who was associated with lightning and death.
Totec, Guardian of Light, had led his army against Xolotl's army of darkness many years ago. Totec defeated and expelled Xolotl. Totec then imprisoned himself at the Temple of Light ready to awaken should the Mirror of Smoke be removed.
In 2010, a man named Vasco removes the Mirror which releases Xolotl. Totec soon awakened but Xolotl escaped claiming to plunge the world into to darkness. Totec and his new ally, Lara Croft, then set out to stop him.