Professor Kurian Fernandez (Nedumudi Venu), a convict, escapes from jail along with Raghu (Ganesh Kumar), his cell mate. After a failed attempt to chase and nab the duo, the officials draws out several plans to capture both. Police authorities strongly feel that Fernandez will land up in Banglore and may try to meet up with his only daughter. Unnikrishnan (Mohanlal) and K.Purushothaman Nair (Jagadish), two inspectors from Kerala Police, are sent to Bangalore to follow the activities of Gaadha (Girija Shettar), daughter of Fernandez. Upon reaching Bangalore, Unnikrishnan meets Peter (Mukesh), his college mate, who is also now an inspector with Karnataka Police. Unnikrishnan and Peter make up a team and sidelines Purushothaman Nair, who struggles hard to cope up with Kannada language. The police team stays at a room just opposite to where Gaadha stays as a paying guest. Gaadha, working at an advertisement agency as a copy writer is staying along with Maggie Aunty (Sukumari), who is constantly in fight with her son (Kuthiravattom Pappu). Unnikrishnan and Peter, who are born flirts, are more interested in drinking and playing cards than investigation. K.P.Nair tries to report this to the authorities, but fails in getting both in control. Unnikrishnan slowly develops a crush towards Gaadha, which gets transformed into a full-fledged passion, but Gaadha never accepts it. Unni befriends with Maggie aunty and tries all ways to woo Gaadha. Meanwhile, Unni and Peter finds out that Fernandez is in the city and is constantly in touch with Gaadha. The police commissioner (M. G. Soman) is in all efforts to nab Fernandez. Unnikrishnan decides to use Gaadha to reach out Fernandez. Gaadha reveals to Unni about the past of Fernandez, when he was a college professor, who was loved and cared by the students. The sincere professor questioned the college authorities on many administration malpractices, which made him a dust in their eyes. The son of the police commissioner was punished by professor, which led to serious fracas in college and authorities were forced to take action on him under severe protests from students. In retaliation, he attacked professor while traveling with a female student. The girl was raped and killed and the professor was falsely convicted in the case. Now, professor is out of jail to avenge on it. Unnikrishnan tries to convince professor with the help of Gaadha, but he fails to give up. Meanwhile, an old man, who is a client of the ad agency, where Gaadha works, likes her and asks her to join him as his secretary abroad. Gaadha, who had by then developed a soft feeling towards Unni lets him to bring his mother (Kaviyoor Ponnamma) to see her. At the same time, Professor succeeds in killing the son of the commissioner. He orders a shoot at sight at Fernandez. Professor goes berserk and loses mental stability and decides to plant a bomb at the city stadium, which might kill hundreds of civilians. Unnikrishnan asks Gaadha to make him give up this heinous plan, but he refuses. That evening, Fernandez plants a bomb, but police team under Unnikrishnan corners him and takes him to the tower. Professor, despite repeated requests denies to explain how defuse the bomb. But Unnikrishnan successfully defuses the bomb, thereby saving the lives of hundreds. But Gaadha, who actually wanted to join with Unni, couldn't join with him and decides to go with the old man to London. The film ends with both the cars with Gaadha and Unni stopping at a junction, when the signal turns green, they move to opposite roads.

• Mohanlal as Unnikrishnan
• Girija Shettar as Gaadha ( Voice dubbed by Bhagyalakshmi)
• Nedumudi Venu as Kurian Fernandez
• Saleema as Mercy
• Sulakshana as Kurian Fernandez's Friend
• Mukesh as Peter
• Soman as Police Commissioner of Bangalore
• Jagadish as K. Purushothaman. Nair
• Kaviyoor Ponnamma as Unnikrishnan's mother
• Sukumari as Maggie Aunty (Gaadha's landlord)
• Manian Pillai Raju as Harihar Iyer
• Ganesh as Raghu
• Janardhanan as M.P.
• Cochin Haneefa as M.P.'s Lawyer
• Kuthiravattom Pappu (cameo role) in a comedy scene

The songs of this film were composed by Ouseppachan with lyrics penned by Shibu Chakravarthy.

• The story has certain subplots inspired from the American movie Stakeout.
• Vandanam was later remade in Telugu as Nirnayam by Priyadarshan, starring Nagarjuna Akkineni and Amala.
• Girija Shettar was chosen for the role after Priyadarshan watched her in Geethanjali. This was her only Malayalam film released, as her second film Dhanushkodi directed by Priyadarshan starring Mohanlal and Raghuvaran was shelved.^[3]
• The climax of the film was heavily criticized, saying that Unnikrishnan and Gadha should have at least met together before saying goodbye. Recent criticisms also go to the lack of mobile phones in India at that time