Hariharan Pillai Happy Aanu movie is all about Hariharan Pillai (Mohanlal) who is a contractor and civil engineer to boot. His crew is Vasu (Jgathy) who is a carpenter, Velappan (Cochin Haneefa) who is supervisor and Sundaran (Salim Kumar) who is a painter. They all lead a happy life till one day Hariharan learns that Satyapalan was cheating him and had no intention of giving back the money he borrowed.Kavya (Jyothrmayi) who is daughter of Satyapalan. She falls in love with Hariharanpillai and helps him in getting his money back.