Four youngsters on vacation meet up with an old friend who had moved to Chennai. His accounts of dalliances with the opposite sex and life in the city arouse their repressed desires.

This is a film on moral policing. When this film was produced, the term `moral policing' was not in the public use by the activist circles or intellectual circles. It was produced in 1993. Perhaps, the film was a bit ahead of its time . More and more cases of moral policing were discussed decades later.. The victims and survivors of moral policing in India include women, religious minorities, sexuality minorities, Dalits, Adivasis, marginalized nationalities, marginalized linguistic cultures, marginalized regions and marginalized skin colours in India. Ilayum Mullum is based on certain real incidents that took place in Kerala.

Kottayam Kunjachan, a small-time thug, gets out of jail after serving a term of seven years for killing a person. Once out, he tries to lead a good life but gets embroiled with a family feud.

Sethumadhavan accidentally kills a criminal to save his life and is sent to prison. After completing his term, he tries to lead a happy life, but his past makes it all the more difficult.

The only way Gopalakrishnan can escape from certain bankruptcy is to sell the property he owns in the city and use the proceeds to settle his debts. To do that, he has to evict his tenants from there first. Unfortunate for him, his tenant is the feisty Meera and her family, who absolutely refuses to vacate the house. Gopalakrishnan uses an obscure clause in the contract to take up residence at the house, and tries his best to smoke his tenants out.

While working the night at an ATM, a security guard, who is the prime witness in the case against a powerful industrialist, happens across a mysterious man named Eesho. They engage in a conversation and the guard pours his heart out to the stranger before realising that Eesho may not be a friend. Who is Eesho and what does he want?

Arjun, an athlete, becomes a star of his college after he breaks another athlete, Tinu's, record. Unable to stomach Arjun's popularity, Tinu takes the competition between them to a personal level.

Sethu aspires to become a police officer to fulfil his father's dream. However, his life turns upside down when he intervenes in a scuffle with a criminal to save his father's life.

Sushma's parents get her engaged to Kishore. After knowing about her parents' plan to get divorced after her marriage, Sushma devises a plan to prevent it.

Krishnan Unni tries to settle the dispute between two feuding families. In the process of doing so, he ends up falling in love with Sreebala, who belongs to one of the families.