He even wrote science fictions and thrillers. As Debjani Sengupta observes in her essay Sadhanbabu's Friends: Science Fiction in Bengal from 1882-1961:
...he [Mitra] also wrote brilliant and innovative science fiction. He had himself stated that SF not only talked of utopias, but that the best of them were based on firm scientific temperaments and facts. Two of his most well known stories are Piprey Puran (“The Story of the Ants”) and Mangalbairi (“The Martian Enemies”). Piprey Puran begins with a dislocation of time from present reality: “This happened many years ago. Everything was strange then... The Earth was beautiful to look at! The ground was covered with soft green grass. Countless varieties of plants sported many hued flowers, and at night the sky was covered with thousands of stars – it was a wonderful sight”. This displacement, when our present has become a thing of the past, introduces a comic note in an otherwise sombre story. This future world, now real, is overrun with Ants, huge in size, intelligent and organised. They have defeated the humans in battle, having taken them completely unawares. When humans were busy fighting each other, the Ants had begun their preparations to take over the planet. Six feet tall, they had emerged from their hideouts in the Andes Mountain and had begun their assault in the year 7757. One by one the cities of Peru, Venezuela and Ecuador came down like blocks of cards. A cavalcade of monstrous Ants had completely surrounded the few remaining humans and had annihilated them. The only man who escaped unscathed was Don Perito who escaped to Mexico. He was the first human to describe the destruction wrought by the Ants. Within a few years the Ants had taken over Guyana, Brazil, Bolivia and Argentina. The weapon of mass destruction that they used was a powerful bomb attached to the body of an Ant. They also used advanced technological weapons. In the battle that they waged with the humans, the Ants used a kind of searching, powerful light, somewhat green in colour. This light took away human sight in an instant. Under this onslaught all the nations forgot their enmity and came together to fight the common enemy.
This story of the battle of the Ants and Humans is broken into small sub-sections with first-person narrations. The first narrator is the storyteller who begins the story. Soon it is broken by the diary of Asesh Roy, an explorer who had first seen the Ants in 6757. The third narration is by Señor Sabatini, a famous writer of Rio de Janeiro who describes the third deadly attack by the Ants. The fourth and final narration is by Sukhomoy Sarkar, who was imprisoned by the Ants for five years and who gives the most comprehensive details of the social and economic organisation of the Ants. These breaks in the narrative structure create very interesting fissures in an otherwise continuous story. They not only make the impossible appear possible (because of ‘eye-witness’ accounts), but give a certain detachment to the narrator so as to emphasize the moral of his tale. This moral is to be found in comparing the Ants with humans, in which the humans are perhaps found wanting. The description by Sukhomoy Sarkar of the society of Ants makes this clear. The Ants live in an advanced democracy where there are no differences in wealth. What they do have are Ants of differing abilities. The intelligent Ants provide the scientific and technological know-how and are strategists who look after the state. They are highly advanced compared to humans in knowledge and social structures, and have a strict sense of justice. The moral that we see in Piprey Puran can also be seen in Mangalbairi. When the Earth is attacked by Martians who poison its entire ecosystem by planting a new kind of seed that grows into a deadly flora that spreads like wildfire, all nations are united to fight this common enemy. “In this hour of danger... the one cause of happiness is that... humans have forgotten enmity as if by some magic. The whole world is united today”. In both these stories Mitra hints at a time when the very existence of humans will be endangered, when common flowers and trees will be a thing of the past.
Although these are more popular among Bengali-speaking school children and teenagers, they are popular among an older generation of literary aficionados as well. In particular, his creation of the character of Ghanada (meaning elder brother Ghana) may be seen from many perspectives: although Ghanada is apparently a disinterested unemployed middle aged male, and who can apparently weave adventures almost at the drop of a hat, the adventures themselves cover themes ranging from crime, human ingenuity, science, history, geography, metaphysics and philosophy. In terms of facts, they are amazingly accurate. It is obvious that while Ghanada himself has not been involved in any of the adventures he claims to have taken part in, he is certainly a very learned man with an exceptional gift for storytelling. Ghanada may be seen as Mitra's parody or caricature of the Bengali urban middle class celibate intellectual, who is at home in the world of books and knowledge, but has little practical experience whatsoever. It is also interesting to note that like Satyajit Ray's Feluda, the older Ghanada although not abhorring the opposite sex, is not entirely at ease with them either. He stays at an all-male hostel and maintains an almost frugal existence. Ghanada is a self educated person and his education is mostly due to time spent at the local libraries. In a way, it could be argued that these stories also reflect larger patterns of social transformations.
Another masterpice of his creation was the character of "Mejokorta". Mejokarta was a famous "Bhootshikari", meaning ghost-hunter in Bangla. The series of Mejokarta, although not as long as that of Ghanada, has left its prominent mark in the genre of ghost stories in Bangla.
(For novels centered around the character of Ghanada, see the article on Ghanada)
Nana Range Bona is not only a short story collection, but it is the only known autobiography of Premendra Mitra.