A normal day... A little face ...A string of clues ... A mysterious case ...It's a regular day at Gulmohar Complex. Spunky, independent, 75 year old Naani is on her way back home from her daily morning walk. Suddenly her eye catches the face of a little girl peeping nervously from a 3rd floor window. The flat belongs to a newly arrived childless couple.

The girl hides away quickly. Naani's intrigue about the little girl leads her to a possible murder. Naani finds herself in the middle of a mystery where some people will come to her aid, some will be indifferent and some will prove to be dangerous. When the CID dismisses Naani's story due to lack of hard evidence, she transforms into a detective.

She uses her home-spun common-sense and logic and she carries out her investigation in classic "whodunit" style. Of course, Naani's rather eccentric methods of investigation lead to many quirky and humorous incidents. Her unusual team of deputies comprise of her 2 inquisitive little grandchildren, her divorced daughter and a couple of teenagers.

The search for one lost little girl leads Naani & Co. to a racket where the stakes are high, the criminals are ruthless, and their leader is powerful. Once Naani gets too close to their trail, she endangers herself. She finds herself sharing the same plight as the little girl she had seen in the window. Naani's team of amateur detectives get together and finally win the day with a little help from the CID.At the heart of this story is the terrified, kidnapped little girl. Her plight acts as a reminder to the audience that Naani's mission is a race against time. And yet, this adventure has a positive effect on all the characters that get involved. Bridges are built, relationships blossom, lessons are learnt.

The two squabbling teenagers fall in love, there is a whiff of a romance between Naani's divorced daughter and the dashing CID Inspector. Old Mr. Pal finds a renewed energy and interest in life. And of course, a lost 4-year-old little girl is finally re-united with her mother. This film has all the ingredients of an entertainer - humour, suspense, emotion and a bit of insight. Detective Naani is a film that will leave the audience feeling good.