A Madras Mystery opens with two young men exchanging a cryptic code about a location, in Chennai, to carry out their 'operation.' A string of abductions from various parts of the city sends tremors amongst the ruling class in Tamil Nadu.

The State is embroiled in caste clashes and only a few months are left for the general elections. Power battle hots up within the ruling party as various heavyweights jostle for cabinet berths.

As Ashwin IPS begins his investigations into the kidnappings, he is stumped by the unpredictable turns that await him. Who are the real forces behind the kidnappings? Are they to settle political scores? Or are there larger conspiracies behind the captures? Will Archana, Ashwin's friend, help him solve the case?