On the 40-year anniversary of Sir Alex Ferguson's arrival at Manchester United, this is the definitive biography of the club's greatest manager - told through previously unheard and unpublished tapes.

The story of Sir Alex Ferguson's success at Manchester United is one of the most compelling in the history of world sport. Everyone knows how it went. Alex Ferguson came to Manchester United from Aberdeen; he overcame a tough start and created a dynasty where he won thirteen league titles, two European Cups, and a knighthood. That story has been told through books penned by Ferguson and his former players. Now, though, this story is told with a difference.

Using 400 hours of exclusive, previously unheard or published audio archive from 1986-2013, contemporaneous interviews with Sir Alex Ferguson and many of his players, and brand-new interviews, the most successful era in football management history is brought to life in the most remarkable, intimate, and forensic way.

Written by Manchester United historian Wayne Barton, the book takes us through the corridors of the Cliff, Carrington, and Old Trafford. It is a fly on the dressing room wall of Manchester United and their opponents. It is a recorder at press conferences. It is a friend next to Alex Ferguson at the most vulnerable moments. It takes the voices belonging to those who knew, worked with and against Ferguson, and encountered him in his full glory.