After he is diagnosed with an incurable brain tumour, and told he has only three to six months to live, wannabe actor-cum-professional conman Shen Mo decides to spend his remaining time doing something more meaningful and for the benefit of society. In the past he has helped the police on several cases, though always kept a low personal profile; now he has decided, with his geeky partner Du Yu, to personally infiltrate some local criminal gangs, including one, led by Yao Dezhi, that sells fake medical supplies and another, led by gangster Jia, that practises phone scams..