The Turks are sort of a secret organisation created to do Shinra's dirty work. Tasks such as, recruiting for SOLDIER, kidnapping and murder are only some of the things the Turks are assigned to do.
The Turks are made up of 4 members, Reno, Rude, Elena, and Tseng. They are under the command of Rufus, who recently became president of Shinra Inc. after the death of the previous president who was his father. One of the Turks' current objectives is to capture the last surviving Ancient, Aeris Gainsborough. Now is Cloud going to let that happen?