The series, which is fronted by Alan Yentob, will run to five programmes, starting on June 28 with The Man Who Forgot How To Read And Other Stories.
The third show, which airs on Tuesday July 12 on BBC One, is called Lennon In Limbo and examines Lennon and Yoko Ono's move to New York, including their battles against the US immigration services and Lennon's "lost weekend".
The film features never-before-heard studio recordings from the Double Fantasy sessions and previously unheard outtakes from Lennon in concert. Yentob has interviewed Ono for the film, as well as people who worked closely with Lennon during this period, including Elton John and photographer Bob Gruen.
Lennon also features in the fourth programme of the series, Harry Nilsson: The Missing Beatle, which airs on July 19.
It tells the story of Nilsson, a friend of Lennon's and celebrated songwriter, and includes home films, music videos and segments from the unreleased documentary made during the recording of Son Of Schmilsson, Did Somebody Drop His Mouse?
Interviewees include Robin Williams, Yoko Ono, Van Dyke Parks, Randy Newman, Ray Cooper and Micky Dolenz.