Season 4 and special announced
BBC teases Season 4 of Sherlock, promising there will not only be three new episodes but a “special” as well.
"Miss me?" #Sherlock, the hit @BBCOne drama, will return for a Special, followed by a series of three new episodes. #221back
— BBC One (@BBCOne) July 2, 2014
As of now, no date has been announced though producers have announced to begin filming in January and are speculating for a late 2015 release.