In 1942 Calcutta in British-ruled India, student Byomkesh Bakshy is approached by a classmate, Ajit, whose father Bhuvan Banerjee, a chemist, has been missing for more than two months. Byomkesh believes that he has been killed and his dead body kept hidden somewhere. During the investigations, he finds that Bhuvan Banerjee''s murder is part of a bigger plot involving local political leaders, Chinese drug smugglers and the Japanese Army, fighting the war against the British in South-East Asia. In the midst of all this chaos, Byomkesh must save an innocent person convicted of murder, solve a puzzle about the chemist''s betel ingredients, and overcome his own self-doubts while unraveling the mystery of an anonymous and dangerous enemy who plans to make Calcutta the drug-capital of the world.