Call of Duty: Modern Warfare 3 (abbreviated as Call of Duty: MW3) is an upcoming first-person shooter video game currently in co-development by Infinity Ward and Sledgehammer Games, with Raven Software assisting multiplayer development. It will be the third installment in the Modern Warfare series, and the eighth Call of Duty installment in total.
The game will immediately follow the events of Call of Duty: Modern Warfare 2, where Russia continues its invasion of the United States of America, and has also expanded its offensive to Europe, including England, France and Germany. It has also been reported that the game's finale will be set in the city of Dubai.
Source: Wikipedia, "Call of Duty: Modern Warfare 3", available under the CC-BY-SA License.