Kotaku has acquired images of what is currently codenamed 'Assassin's Creed Unity' which point to an 18th Century French setting for the next Assassin's Creed title.
Paris landmarks revealed include Notre Dame and the Seine River and it's most likely that the game will be set in or around the French Revolution which began in 1789 and may also include the Reign of Terror and the rise of Napoleon. Much of France's history during this period could be tied into Assassin's Creed mythology with Pieces of Eden explaining the events that occured throughout the period.
The name of the assassin in Unity is said to be Arno.
It seems that Unity is set for release on PS4 and Xbox One with Assassin's Creed Comet coming to PS3 and Xbox 360. There's no word yet on PC or Wii U versions of either game but both are planned to launch this year. Assassin's Creed 4 director Ashraf Ismail recently said that Ubisoft will continue to develop Assassin's Creed titles for last-gen consoles and making two games would allow for Unity's developers to avoid making compromises for the older hardware.