Namak Halaal is about being loyal to the hand that feeds you, even if it means you lose everything in the process. Savetri, ( Waheeda Rehman ) gave up her son, Arjun ( Amitabh Bachchan ) to keep a promise to her dying husband, who had cheated his kind-hearted employer. Savetri brings up Raja ( Shashi Kapoor ), the heir to the business empire, while Arjun is raised by his Grandpa ( Om Prakash) . In order to make a man out of him, grandpa sends him to the city, where Arjun finds a job in a hotel owned by Raja. At the hotel Arjun meets and falls in love with a co-worker, Poonam ( Smita Patil ).
Raja grows up believing Savetri is his mother but when attempts are made on his life, he suspects that she is the person behind the attacks. A heartbroken Raja returns tot he hotel where he meets Arjun and they become friends. Arjun watches helplessly as mother and son face off on what to do with Raja's inheritance. When another attempt is made on Raja at the hotel, Arjun decides to find out who is behind the attacks.
He begins to even suspect Nisha ( Parveen Babi ), his girlfriend, a cabaret dancer who needs money very badly?..Directed by Prakash Mehra, the film?s music is composed by Bappi Lahiri and includes ?Pag Ghungroo Baandh? and ?Raat Baaqi Baat Baaqi?.