In Rasavathi, Santhakumar pits a soft-spoken and astute Siddha doctor Sadasivapandian (Arjun Das) with Kodaikanal’s new inspector Parasuraj (Sujith Shankar) who suffers from unresolved psychiatric illness. Also new in town is a resort’s manager Surya (Tanya Ravichandran) who, unsurprisingly, makes a bond with Sada. Perturbed by seeing the happy couple, Parasu goes out of his way to try wreaking havoc in their relationship. While it initially looks like the work of a narcissist being unhappy seeing others happy, there’s more to it than meets the eye.