A retired officer looks for a mole.

George Smiley has been pushed out of the service and is retired. Oliver Lacon comes to his house at night because a field officer, Ricki Tarr, has come back with a story. Tarr was in Istanbul, met a Russian woman, and was told there is a Soviet agent at the top of British intelligence.

Smiley is asked to find the man without using the service to do it. He works from a hotel room with Peter Guillam, who takes a file out of the building, and Mendel, a retired policeman.

Control, who ran the service, is dead. Before he died he gave five men code names from a rhyme: Tinker, Tailor, Soldier, Poorman, Beggarman. One of the five is the agent.

Smiley reads old files and interviews people who have been pushed out as well: Connie Sachs in Oxford, and Jim Prideaux, who is teaching French at a boys' school. Prideaux was shot in Czechoslovakia during an operation that was not on the books.

Smiley also thinks about his wife Ann, and about a meeting years earlier in Delhi with a Russian officer called Karla.

A house in London is watched for several nights. Somebody comes to it.