Mazha movie begins teenager Bhadra (Samyukta Varma) getting infatuated with her music teacher Sastrigal (Biju Menon). Her creative talents for poetry start to flourish, under his influence. But then the usual villains in Indian movies appear – the parents. Her parents whisk her off and he is obliged to marry a village belle.
Next we see Bhadra becoming a doctor (like her father) and married to Chandran (Lal) who is a well-off computer engineer.
Chandran happens to see her diary one day and the relationship goes for a toss. Of course, there are no names in the diary. So he goes off to doubt every male in her life – including the elderly senior doctor . He becomes a victim to his drinking and dies of related illness.
Bhadra sets out in search of her old flame to Madurai where she discovers that Sastrigal also has lost much – his wife is a basket case by now, and the final shock is when she finds out that he has lost his beautiful voice to cancer too