Shubho Mahurat marks the ceremonial start of shooting for a new feature, and the opening sequence unfolds with a grand reception that feels like a festival of cinema. An NRI producer and former leading actress, Padmini Chowdhury, Sharmila Tagore returns to India to invest in the project. Her second husband Sambit Roy, an out-of-work director, Sumanta Mukherjee is chosen to direct. Padmini insists on casting the retired actress Kakoli Sengupta, the veteran star Kalyani Mandal, in a pivotal role. Covering the event are a local magazine journalist, Mallika Sen, Nandita Das, and a freelance photographer, Shubhankar Chowdhury, Anindya Chatterjee. The production crew also includes Kalpana Sengupta, a makeup artist Moumita Gupta, and Sunil Mehra, a camera assistant.
At the reception, Kakoli collapses and dies soon after, leaving everyone stunned. Police suspect an overdose, but the autopsy reveals strychnine poisoning. Investigation officer Arindam Chatterjee, Tota Roy Chowdhury, initially suspects Kakoli’s husband, who is entangled in an extramarital affair, though the poison seems to have entered Kakoli’s system at the party. Mallika recalls that Kakoli only had a soft drink at the gathering, and that drink was actually meant for Padmini. This key detail prompts a broader inquiry as Pishima, Rakhee Gulzar, counsels Mallika and hints that another murder could be looming. As the investigation unfolds, a growing mutual attraction arises between Mallika and Arindam, and between Mallika and Shubhankar.
Pishima learns that Shubhankar is not a distant stranger to Padmini: his uncle was Padmini’s first husband, and she had once shown him affection as a child. Kalpana confides in Padmini about her relationship with Sunil Mehra, a married man who refused to fund treatment for Kalpana’s daughter. Moved, Padmini vows to help Kalpana and shares a painful memory of her own dead son, who succumbed at sixteen to a congenital disorder. Kalpana makes a discreet exit from Sunil’s place after having another soft drink, and she is later found dead; Sunil is arrested.
Pishima listens to Mallika’s interview with Kakoli, questions Shubhankar about Padmini, and then arranges a call with the director of Kakoli and Padmini’s last film. She publishes an anonymous piece in Mallika’s magazine about infections during pregnancy and their impact on unborn children, in the very edition carrying Padmini’s interview. A copy lands with Padmini, whose curiosity and resolve quicken as Pishima recounts how she has solved the mystery.
During their final film together, Padmini was pregnant, and Kakoli had a contagious illness that Kakoli unknowingly transmitted to her co-actor, eventually affecting the unborn child. Padmini’s act of revenge—poisoning Kakoli—happened after Kakoli’s potential blackmail was deemed dangerous, and Kalpana’s earlier sighting confirmed the motive. Pishima reveals to Padmini that she is a devoted fan and that her story will be kept safe. Padmini returns home, only to be found dead by suicide, and in a final gesture of loyalty she sends an autograph to Pishima along with a long fan letter, also promising support for Kalpana’s daughter’s treatment.
In the closing moments, Mallika confronts the ethical knot of love and loyalty. She asks Shubhankar whether it’s possible to love two people at once. He reflects that Padmini once said something similar, and he explains that she proved it by losing herself in the past: after the birth of her son, she forgot about Shubhankar entirely, to the point of not recognizing him at the reception. This confession seals the emotional gravity of a life lived in pursuit of art, memory, and the shadows that haunt those who chase both.
