In a small town in Goa steeped in azure seas and sultry secrets, the chief of local police station, Siddharth (Emran Hashmi) finds himself caught in the eye of a storm…and about to get blown away.

Siddharth, who is going through a divorce with his wife, Sonia (Shamita Shetty) whom he still loves, finds himself involved with a local married woman named Anna (Udita Goswami). Unable to cope with the pressures of his wife's success who is in the special police force, he continues his secret and dangerous relationship with Anna.

Things get even more complicated when Siddharth realizes that Anna's husband, Shawn (Sameer Kochhar) is a wife beater and Anna is dying from cancer. Being a good soul, Siddharth does not have it in him to abandon this woman who seems to have given him some affection in recent times.

In the heat of the moment, Siddharth takes an irrational decision to give Anna the money he recovered in a drug raid, for her medication in a final effort to save her. Things are not what they seem since Anna dies in a fire that very night. Siddharth now races to uncover a murky tail of drug money, murder and deceit, because all the evidences points to him.

With his wife heading the case, Siddharth is now in a race against time to find out the real truth behind Anna's murder, recover the drug money and also win his wife's love back.

After a bunch of wild goose chases, Siddharth finds out that Anna is very much alive and was actually controlling Shawn and Siddharth in the whole plot for getting the Insurance money. Siddharth finds this in just nick of time and while confronting Anna with the truth, Anna points a gun at him. In the scuffle that follows, Sonia shoots Anna and she provides the alibi for him stating that Anna's death was an accident.

The movie ends with Siddharth recovering the lost drug money and his wife.

• Shamita Shetty as Sonia Mehra
• Emran Hashmi as Siddharth Mehra
• Udita Goswami as Anna
• Sameer Kochhar as Shawn
• Ninad Kamat as James
• Vishwajeet Pradhan as Inspector Shah

The soundtrack of Zeher was composed by Anu Malik, Roop Kumar Rathod, Mithoon, Naresh Sharma, Jal (Band) & Atif Aslam. "Agar Tum Mil Jao" is copied from a Pakistani song by the same name sung by Tasawwar Khanum (1974).

The tracks like 'Agar tum mil jao' and 'Woh lamhe' attained high popularity. The compositions were recreated and directed by Anu Malik (Roop Kumar Rathod's compositions) & Mithoon & Naresh Sharma (Atif Aslam compositions). Singers like Shreya Ghoshal, Udit Narayan, Atif Aslam & K.K. crooned for the songs in the album. Lyrics were penned by Sayeed Quadri & Shakeel Azmi. The songs Agar Tum Mil Jao & Jaane Jaa Jaane Jaa were chartbusters while other songs were also extremely popular with the song Woh Lahme being a big rage among the youth. The soundtrack was ranked on 5th position in the year 2005 by all-time music sales. According to the Indian trade website Box Office India, with around 18,00,000 units sold, this film's soundtrack album was the year's fourth highest-selling.

Nominations:

• Filmfare Award for Best Male Playback Singer (2005) - Atif Aslam
• Filmfare Award for Best Female Playback Singer (2005) - Shreya Ghosal
• Zee Cine Award for Best Popular Track Of The Year (2005)
• Zee Cine Award for Best Playback Singer - Male (2005) - Atif Aslam
• IIFA Award for Best Male Playback Singer (2006) - Atif Aslam
• Screen Award for Best Debut Director (2006) - Mohit Suri
• Screen Award for Best Playback Singer - Male (2006) - Atif Aslam