An experimental romantic thriller, Solo is the story of four different men, their love, rage and afterlife. Through four elements - water, air, fire and earth, they also represent different facets of Lord Siva.

Isabella, a guide, falls in love with one of her customers, Unnikrishnan. But every time they meet, he refuses to accept her. Moreover, she struggles to deal with the difficult situations at home.

Venu is an orphan who works as a taxi driver. He is mistakenly nabbed by the police for kidnapping Gopika Varma, an NRI girl. Will he be able to prove his innocence?

Balan, a teacher, has a mentally unstable uncle. There is a belief that the family is cursed to have a lunatic at all times. When the uncle passes away, people believe that Balan will be the next.

Aleena, a widow, cherishes her dead husband's memories and dismisses the marriage proposals. Her four-year-old daughter gets close to a man over phone. Though sceptical, Aleena agrees to meet him.

The film depicts a famous Malayalam writer's emotional relationship with an intellectual who leads the life of a simple farmer in a remote village. The story unfolds through the writer's bus journey to visit him.