Sivappu Sooriyan (Red Sun) is a 1983 Tamil action film directed by Muktha Srinivasan and starring Rajnikanth, Radha, and Saritha.
The film follows Vijay, a merchant navy officer who returns home on leave to find his sister Selvi missing along with her husband Vishwanathan. With the help of Chitra, he locates Selvi, but she is devastated due to Vishwanathan's disappearance after testifying against a dangerous criminal in court.
Vijay decides to disguise himself as a smuggler to infiltrate the underworld and rescue his friend Vidyasagar, who can help devise a plan to save Vishwanathan. The film explores Vijay's journey as he navigates the underworld to retrieve his friend and bring normalcy back to Selvi's life.