There are mystical items called Landtool that the ruler of Harappa Land, a land of robots, has instructed his people to find. Two of them, Robotack and Kamerock arrive in Yumegaoka and make friends with detective Kaoru Sugi and his nephew Kakeru. The two join Sugi's agency in their quest to find the Landtool and also solve crimes in their small town. At the same time, they must thwart the Gold Platinum P.D. Agency, headed by Robotack's brother and arch-enemy Torabolt, from finding and profiteering from the Landtool.
Tetsuwan Tantei Robotack provides examples of the following tropes:
- Crossover: The cast of Robotack meets the cast of B-Robo Kabutack in a crossover special.
- The Hero Dies: Robotack dies in the final episode. Actually not.
- Heroic Sacrifice: Robotack finally vanquishes the forces of evil in the final episode, but at the cost of his life. Or so it seemed.
- Pun-Based Title: Although Tetsuwan is an actual Japanese word, Wan is also the Japanese sound of a dog barking.
- Spoiler Title: Take a wild guess what happens in the last episode, Robotack's Death at Sea.
- Super Mode: Special Mode.