Watch Karthikeya for Free: How to Stream the Movie Online at 123Movies. . Nikhil Siddharth and Swathi Reddy are back once again onscreen with Karthikeya. The mystery of the Subramanian Swamy temple which has remained closed for years is the crux of the movie. Local people in the village are curious why the temple has been locked up for years? The lead protagonists take the initiative to solve the mystery.