 Karan Kapoor and Rhea Prakash meet for the first time in a flight bound from Delhi to New York . They just cannot stand each other : Rhea is disgusted by Karan s flirtatious mannerisms and Karan is frustrated because of Rhea s overt seriousness . They have a massive fallout and part ways , vowing never to see each other s face again . Destiny brings them together again at Rhea s marriage ceremony three years later and the mars vs. venus war continues . Rhea gets married and leaves for USA . Four years later , Karan has become a successful cartoonist and travels to Paris to visit his father (Rishi Kapoor) . Co-incidentally he meets Rhea again and learns that her husband is no more . Karan tries earnestly to bring happiness back in Rhea s life by promising her mother that he will find a suitable groom for Rhea but the duo never realizes that they are drawing closer to each other . Will love happen ? And if it does , will the star-struck couple ever admit to it ? Watch the breezy romantic musical comedy Hum Tum for the answers .