The two hour film documents how Lennon and Yoko Ono became vocal peace activists in the late 60s and early 70s, and by aligning themselves with radical revolutionary figures, drew the attention of the Nixon Administration.
Outside of his Ghandi-esque "Give Peace A Chance" efforts, Lennon met with and provided support and money to radicals Abbie Hoffman, Jerry Rubin, and Black Panther Party founder Bobby Seale, and this made Nixon and his cronies ramp up their paranoia towards Lennon and Ono.
They began to harass him - tapping his phone, following him, etc. The loudest shoe dropped when they revoked his temporary Visa and began motions to deport him.
A courageous lawyer took Lennon and Ono's case on and was able to string it out until the Nixon administration crumbled and they were finally granted permanent residence status in the mid 70s.
Not to get deep into politics on this blog, but the parallels between the power mongering and fear of freedom of speech between the Nixon administration and the current regime in the U.S. is shocking.