Mastiii 4 revolves around the same concept of three friends, Amar (Riteish Deshmukh), Prem (Aftab Shivdasani) and Meet (Vivek Oberoi), based in the UK, who are still unhappy with their boring marriages and trying to have a relationship outside their marriage. Amar works in a zoo who helps animals in mating. Prem is a doctor, while Meet works in the automobile industry. Amar, Prem and Meet are married to Bindiya (Elnaaz Norouzi), Geeta (Ruhi Singh) and Aanchal (Shreya Sharma). The trio too are not happy with their married lives for various reasons. They attend the tenth wedding anniversary of their friends, Kamraj (Arshad Warsi) and Menaka (Nargis Fakhri). Bindiya, Geeta, and Aanchal are envious of Kamraj's intense affection for his wife. Meet, Prem, and Amar suspect Kamraj of having an extramarital affair. When they see Kamraj enjoying fun with ten girls, their suspicions are validated. Surprisingly, Menaka doesn't object when they tell her about it. At this point, Kamraj tells the three of them that his wife has granted him a "Love Visa." It implies that he is permitted to have extramarital affairs for a week. Menaka thinks that when the week-long time is over, Kamraj becomes a faithful husband and stops looking at other women. The "Love Visa" idea intrigues Amar, Prem, and Meet, so they resolve to ask their spouses for one. What happens next forms the remaining plot of this adult comedy drama.