1: Jim Prideaux captured. Some ex-colleague invites Smiley to dinner and keeps asking how incompetent people like Alleline climbed to the top of the Circus. Smiley recalled to service to meet Ricki Tarr.
2: Ricki Tarr tells his story to Smiley. Peter Guillam starts stealing material from the Circus, find missing page on the communication officer list. Smiley sets up his investigation operation.
3: Smiley meets Connie who tells that she was fired for suspecting Poliakov. Flashbacks show the ousting of Control and Smiley.
4: Guillam steals more material from the circus. While doing that, he is called by the top officers to inquire about Ricki Tarr being in England, which they suspect because they discovered that his family has come.
5: Jim Prideaux tells his story to Smiley, who cannot easily access the Circus reports about it. When he is returned to England, there was basically no debriefing, and Esterhase already knew about the Tinker Tailor codenames, presumably through Merlin.
6: Smiley hears the story of yet another ousted man, who heard the Russians knew in advance about Jim Prideaux' coming. Toby Esterhase dismissed him for alcoholism.

Tinker Tailor Soldier Spy (film, 2011)

This is not bad, but some divergences to the better BBC miniseries, which presumably sticks more closely to the novel:

in the film Jim Prideaux is captured in a cafe in Prague, in the series it's in the woods. It is therefore much more plausible that he would have been shot.
in the film Peter Guillam is played by Benedict Cumberbatch, who feels a bit young to be Ricki Tarr's boss. Not impossible, but still.
the series is much less chronological, and more flashback based, as new information becomes available. The film is more chronological, which makes it easier to understand, but less interesting at the same time.
in the film they shoot the Russian girl Irina in front of Jim, in the series the fact that she was shot is only known through other sources. The film has more eye candy, which weakens it.
Toby Esterhase is not threatened in an airfield, only in a safe ;house in London.