Post Box No. 27

Miffed at losing a coveted promotion as the area branch manager of Dixi Cola, assistant manager Suresh Kumar (Mukesh) gets drunk with his pals Philipose (Siddique) & Immanuel (Sainuddin), & writes a threatening letter to Suresh's boss Somashekaran Nair (Innocent). However, when it turned out that Suresh was indeed getting that job, they try desperately to get the letter back. To worsen things, Nair gets killed & the letter lands in the hands of the cops, making Suresh & pals the prime suspects. (Summary by iceblox)