Shasanka is a retired teacher who lives with his wife and two daughters. The family is thrown into an uproar after he goes out for a walk and disappears from their lives. Each member of the family reviews her final hours and days with him to try and discover what, if anything led to his disappearance.
Unfortunately the movie Ek Din Achanak is not yet available on HBO Max.
| Writing | Mrinal Sen | Writer |
| Writing | Ramapada Chowdhury | Story |
| Directing | Mrinal Sen | Director |
| Writing | Shashi Anand | Dialogue |
| Art | Ashok Nag | Assistant Art Director |
| Art | Debashish Ghosh | Assistant Art Director |
| Camera | K.K. Mahajan | Director of Photography |
| Production | Jitesh Basu Thakur | Production Manager |
| Crew | Mukul Chaudhuri | Production Controller |
| Costume & Make-Up | Manu Dutta | Costume Designer |
| Directing | Rashid Iqbal | Assistant Director |
| Editing | Rathin Bose | Assistant Editor |
| Art | Biswanath Das | Assistant Production Design |
| Directing | Rahul Bose | Assistant Director |
| Art | Chakradhar Mahapatra | Assistant Production Design |
| Costume & Make-Up | Debi Haldar | Makeup Artist |
| Camera | Subhash Nandy | Still Photographer |
| Art | Goutam Basu | Art Direction |
| Art | Subrata Debnath | Assistant Art Director |
| Directing | Siddhartha Dutta | Assistant Director |
| Sound | Jyotishka Dasgupta | Music |
| Sound | B K Chaturvedi | Sound Recordist |
| Editing | Mrinmoy Chakraborty | Editor |
| Production | Ravi Malik | Producer |
| Production | Debasis Majumdar | Producer |
| Art | Sunirmal Mazumdar | Assistant Director of Photography |
| Costume & Make-Up | Hara Das | Assistant Makeup Artist |
| Art | Alok Upadhyay | Assistant Director of Photography |
| Costume & Make-Up | Pulin Kayal | Costume Designer |
| Costume & Make-Up | Ram Prasad Kahar | Makeup Artist |
| Sound | Anup Mukhyopadhyay | Sound Designer |
