Kalisundham Raa is family based movie in which, Raghaviah(Vishwanath) and Ram Mohan(Rama Mohan) are brothers in-law. But Rammohan is at loggerhead with Raghavaiah because of a family feud. Raghavaiah is nearing his 60's and its time for his 'shastipoorti' ceremony. It's time for gathering, folks! Upon incessant request from his wife, Raghavaiah decides to invite (for the first time) his daughter-in-law and grandsons who are staying in Bombay.
Raghu(Venky) is the alienated handsome grandson of Raghavaiah. After arriving at Ramapuram from Bombay, he faces embarrassment from the members of Raghavaiah's family. There he meets a childlike beauty Manga(Simran). Manga and Raghu play few pranks on each other and slowly they fall deep in love. But they never admit their love to each other. With his unconditional love towards the family members, Raghu wins the confidence and hearts of them.
Later on Raghu comes to know the real flashback behind the feud between the families of Raghavaiah and RamMohan. Raghu's father is supposed to marry the daughter of RamMohan. Raghu's father prefers his college flame to the maternal uncle's daughter. He leaves for Mumbai and gets married to his sweetheart. A disappointed daughter of Rammohan opts for suicide. rest of the story is how Raghu makes these two familyes get closer each other.