Kembar Siang is about a pair of twins named Awal and Awi (both played Kamal Adli). Awal is the elder of the two and Awi is mentally ill, due to a fever when he was young. Amazingly, Awi has superb memory and an extraordinary ability to count, often tutoring Mazli and Izan after school. The twins have a house and a grocery shop given to them by their late father Haji Sabran. They are rivalled by another grocery shop run by Pak Din Duda (Sabri Yunus) who is not honest and always trying to make a quick buck.

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