On an unknown date, Grima came into the service as the chief counsellor of Theoden, King of the Mark. Grima was a spy of Saruman, attempting to wear down Theoden's will and thus cause him to unwittingly do things that would be to Saruman's advantage. Upon being discovered as a traitor, he fled Rohan, and took refuge in Orthanc with Saruman. Shortly after the destruction of Isengard, he fled to the Shire with his true master. Saruman treated Grima very badly and was eventually slain by him, after which Grima was killed by hobbit arrows.