Zeher is a romantic thriller drama. The movie revolves around a police officer Siddharth Mehra (Emraan Hashmi) who is married to Sonia (Shamita Shetty), a special police officer. Despite being in love with his wife, Siddharth is jealous of his wife’s success, and soon gets involved with another married woman named Anna (Udita Goswami). Siddharth finds out that Anna is suffering from cancer, so he gives her the drug raid money for her treatment. However, things go extremely wrong when Anna mysteriously dies in a house fire the same night. Siddharth becomes the prime suspect of murder, deceit and the theft of raid money. With his wife heading the case, Siddharth must race against the time to find the proof of his innocence.