Chaahat - Ek Nasha revolves arpund two characters Mallika Arora and Rashmi Jaitly. Rashmi lives a wealthy lifestyle in India along with her widower dad, Dr. Sanjeev Jaitly. She aspires to be a singer and dancer, and is encouraged by her friends and dad to take this up as a profession. She prepares her portfolio and approaches R.K. Music Co, which is run by Rahul Kapoor.
Rashmi is also an ardent fan of established singer/dancer, Mallika Arora, a client of Rahul, and always sends her gifts and flowers on every possible occasion. When Mallika fails to impress the public, Rahul is advised to look for fresh talent, and he approaches Rashmi, and together they release their first album which turns to be a major success.
Together they deliver many other hits and also fall in love with each other. Sanjeev initially opposes their romance and eventual marriage as he feels that Rahul and his celebrity lifestyle is not right for Rashmi. He eventually gives in when Rashmi insists on marrying Rahul. A lavish engagement party takes place - and it is after this party that Rashmi will find out that Rahul and Mallika had been lovers, and that both still have strong feelings for each other. Watch what happens when she confronts Rahul, amidst growing publicity about Mallika and Rahul's lives and affairs.