Ila, a young woman neglected by her husband, strives to win him over again by preparing a delicious lunch for him. His lunchbox is picked up by the huge lunchbox delivery service (the "Dabbawallahs"), which delivers to all of Mumbai's firms. In the evening, Ila waits in vain for her husband to compliment her on his lunch treat.
It transpires that there has been a mix-up, and the usually highly efficient delivery service actually gave the lunchbox to Saajan, a solitary man nearing retirement. When Ila realises there must have been an error, she slips a note into the lunchbox in an attempt to find out what has happened. This note leads to many more between Ila and Sajaan.