Rahul Mithaiwala (Shahrukh Khan) is a forty-year old bachelor and lives in Mumbai. Rahul's parents died in a car accident when he was eight years old and it was his grandparents who brought him up. His grandfather has a sweet-selling chain store - Y.Y. Mithaiwala. Before his birth centenary celebration, two of Rahul's friends suggest a vacation in Goa which he accepts. On the day of the birth centenary, his grandfather dies whilst seeing a cricket match. His grandmother tells him that his grandfather desired to have his ashes divided into two parts - to be immersed in the Ganges River (in the north) and Rameswaram (in the south). She requests Rahul to go to Rameswaram and immerse the ashes. Rahul reluctantly accepts her request. On the other hand he was eager to attend the Goa trip, so, he and his friends make plans to dump the ashes at Goa. But, they were forced to change their plan when Rahul's grandmother told him that she would be coming to see him off at the station. This forces Rahul to travel by train and he booked a single ticket on the Chennai Express. He plans to meet his friends after commencing the journey at the Kalyan Junction station from where they would travel to Goa by car.