The Misty Valley Branch Line goes from the Peel Godred Branch Line, south of Peel Godred to Callan Castle. Callan, Black Loch and Callan Castle are located here. Cyril the Fogman also lives close to this line in his cottage.
The line begins just south Peel Godred and travels up to Callan, then through Misty Valley and the line ends and loops around at Callan Castle.
During the fourth season Duck, Oliver, Donald and Douglas were often seen working at Callan. Thomas, Edward, Henry, Percy, and Toby have also been seen working on the line. In the eighth season episode Emily's New Route, when the Fat Controller was assigning new routes for the summer, James was initially given the line before it was given to Emily, who worked the line alone for the rest of the summer.