Badi door se aaye hai is a story of 5 aliens, extraterrestrial people, from a different galaxy, who come to earth with an aim to find their eldest and lost son, 2015. This family consists of 5 aliens - a father, mother, father's brother and their 2 children. Few years back they had lost their eldest son while travelling through our galaxy. Since then they have been searching for him from planet to planet. This hunt has brought them to our planet earth.

Their spaceship crashes in a jungle as they accidentally land on earth. On landing, they are shocked to see our civilization and its form. Later they realize that if they move around in their alien form they will be treated differently or may be taken captive for research and analysis, thus risking their existence. But since they get very strong clues of their lost son to be living on earth, they forcefully take the form of humans and secure their lives.

Meanwhile, after the crash, their son, -426, gets lost. They eventually find him in Sunshine Colony. They find that their alien detector, which rings whenever anybody else of their galaxy is near, keeps ringing in Sunshine Colony. They then get the best area for their aim and they get one row house in that colony and stay there. Taking a human form was very easy as they are born with super natural powers. But the life that they have to lead post taking the human form is the problem. From here begins the journey of this alien family, coming from 5000 years ahead of our human civilization, trying to adjust and accommodate with the diversities and complications of our civilization.

Will they succeed in their plan of finding their missing son, 2015?