Viswasam is an action drama film that revolves around the life of a devoted father, Thiagarajan (played by Ajith Kumar), who prioritizes his family above everything else. He is a straightforward and honest man who works as a lorry driver. His life takes a dramatic turn when his daughter, Rakshitha (played by Nayanthara), returns to India after completing her education abroad. As a loving father, Thiagarajan wants to ensure her safety and happiness.