Tahqiqaat is a crime thriller drama. The movie revolves around twin brothers - Prem and Arun (double role by Jeetendra). Prem moves to a small village and becomes a celibate catholic priest, while Arun joins the police force. Years pass by, and the two brothers grow in their career and lives. However, after many years, Arun contacts Prem, when a woman named Mary (Farheen), from his village, commits suicide and there is no clue to be found about her death. Prem asks to unearth Mary’s corpse, so that he could perform an autopsy. When Arun uncovers Mary’s body, he finds out that Prem was in the coffin, while Mary’s body was missing. A lot of confusion and a series of questions arise in Arun’s mind. The question remains, will he be able to unveil the truth?