Sarika as Sheetal Thadani
Sheetal Thadani is a singer married to Ranjeet the owner of Soundman Industries, a music company. She is trying hard to get her husband Ranjeet away from his habits of poking fun at innocent people. Well aware that her husband is beating his stress by engaging in such activities, she terms his doings as unfair. She decides that leaving him will only teach him what she had been trying for two years.
Rajat Kapoor as Ranjeet Thadani
Ranjeet Thadani is a bored, arrogant music company executive who lives up his upper class existence by attending ?talent dinners? hosted by his friends and him. His life revolves around this stress busting fun which is just not appreciated by his wife. It is his pride that will probably lead to his downfall.
Vinay Pathak as Bharat Bhushan
Bharat Bhushan is a roly-poly officer with the Income Tax department. His innocence and his obsession for singing gets him trapped in Ranjeet Thadani's house. He shares his pain through Hindi songs and a scrap book which contains memoirs of his childhood. He relentlessly tries to be of some help to Ranjeet Thadani, only to make matters worse on every front. A likeable, warm little fellow, he is undeniably a big time goof up.
Ranvir Shorey as Asif Merchant
Asif Merchant apart from being the finest tax inspector of his department is also Bharat Bhushan's best friend. He is as egoistic as Ranjeet Thadani and is always looking to put the other person down. He comes to help Ranjeet at the behest of his friend Bhushan, only to discover his worst nightmare come true!
Milind Soman as Anant Ghosal
Anant Ghosal a music director is an old society friend of the Thadani's. He is the friend in need, who is ready to help Ranjeet in spite of the fact that Sheetal chose Ranjeet over him two years ago. He is ready to forgive Ranjeet for the betrayal and assists him in finding the whereabouts of Sheetal after she leaves Ranjeet.
Bhairavi Goswami as Suman Rao
Suman Rao is the provocative, melodramatic friend of Ranjeet Thadani. A wannabe singer, she is always trying to lure Ranjeet towards herself. Well aware of Ranjeet's past she waits patiently for the day when Ranjeet will reciprocate her love.
Ranjeet Thadani (Rajat Kapoor), a bored, arrogant music company executive hurts his back the night he has found a prize catch for a weekly bring - your -idiot talent dinner hosted by his friends and him. He ends up spending the evening with this idiot, Bharat Bhushan (Vinay Pathak) who tries to help him get his wife (Sarika) back who left him earlier that day. The result is utter chaos let loose by the idiot, who cannot do a single thing without messing it up further.
The plot turns around to be a series of mini disasters that leave Ranjeet's comfortable life in ruins. Call it the idiot's revenge!