Prasab is about the travails and troubles of the Marxists revolutionaries in Bengal. Its about Samiran, a comrade who is imprisoned for life. Another comrade Amol takes care of his wife Pritha and newborn son Piklu. Samiran is released after few years and finds Amol leading the life of an ordinary man with his wife and son. Prithas letter takes him to Ballabhpur in Bijhar where he is happy to find his wife carry out the movement.