Set in the background of lush green England, this tale of two intrepid kids resonates with that most fundamental character traits of adventure and fun, traits that are the raison de'tre of any kid who are looking out for a bit of fun on the wayside. Hari Prasad Dhoonda or Hari Puttar, as he is fondly called, is a bright 10 year old who has recently moved from India to the U.K. with his parents. His father, Prof. Dhoonda is assigned to work on a secret project with the Defense Forces at a remote location in the U.K. He has access to confidential information that is stored on a chip and safely kept at his house. Within days of their arrival in London, Hari's aunt and uncle DK visit the Dhoonda residence with their own as well DK's boss' children. At this point, everything goes for a spin for Hari Puttar. Hari Puttar suddenly feels unwanted, undermined and unappreciated. But Hari has a friend from his fantasy world - Funtoon, who is around when Hari really needs him. Funtoon is a fun character - a 'Masti Ka Boss' and helps Hari cheer up when he is down or when he is upto some Masti. The two are like alter egos who complement each other. To top it, DK arranges a vacation for the entire family and as luck would have it, the next morning, the whole family leaves in a tearing hurry, forgetting that they have left something integral behind - Namely Hari and his little cousin Tuk Tuk. Meantime, an infamous don, Kali Mirchi, assigns two bumbling burglars to steal the secret formula chip from Hari's house. Hari accidentally discovers the mission of the burglars and is determined to save the secret formula from being exposed. The so-called diminutive Hari Puttar embarks on a journey of great adventure and suddenly discovers the self-confidence, creativity and gumption that he did not know he possessed. With his innovative plans, determined wit, and with able support from Tuk Tuk, Hari Puttar manages to not only save the secret chip but also captures the two unsuspecting thugs. Hari's mother in the meanwhile, desperate to get back to Hari goes through her own adventure to reach back home; And when she does, she finds that she had left behind a son and had come back to a little hero.