Oththa Seruppu Size 7, simply known as Oththa Seruppu, is a 2019 Indian Tamil-language thriller film produced, written and directed by R. Parthiban under the banner Bioscope Film Framers. The film stars Parthiban himself as the only character. The background score for the film is composed by C. Sathya and the film has only one song, which is composed by Santhosh Narayanan. The film entered the Asia Book of Records and India Book of Records for having a single person writing, directing, solo acting and producing a film. It was the third South Indian film to feature a single actor after The Guard (2001- Malayalam) and Shanti (2005- Kannada).

Plot

Masilamani (R.Parthiepan) is a suspect in a murder case and cops take him in custody for investigation. The movie starts with a middle-aged Masilamani (Parthiban) being interrogated by police personnel in a police station. The audience gets to hear only the voices of everyone else other than Masilamani. The deputy commissioner is leading the interrogation. Though some other cops in the unit suggest that they better use the typical police interrogation technique (which uses force and human rights violation techniques), the deputy commissioner refuses to approve because there is already a letter from the Human Rights Commission saying that they will be watching over this investigation. At some point, it becomes clear that Masilamani has a kid who needs medication, and even with medication, Masilamani's son is expected to live only for a few more years. Masilamani outwits the cops during the interrogation, and a female psychologist is brought in to help solve the case. It is revealed that Masilamani's wife is dead, and her body is presently held at the mortuary. Eventually, Masilamani starts to confess to not only the one murder he was accused of but also to two more murders, all of which happened using the same modus operandi (MO).