A possible concise summary is:
- A man named Naveen Kumar, who owns a paint factory that pollutes the environment, is killed by a bomb blast after receiving threats from environmental activists.
- CID investigates the case and finds out that the killer is Mohan, a former doctor who suffers from a rare skin disorder caused by pollution.
- Mohan uses his knowledge of the city's drainage system and anaesthetic gas to sneak into his victims' houses and kill them with weapons related to their environmental crimes.
- Mohan also kidnaps Prakash, an activist who saw him at one of the crime scenes, and tries to frame him for the murders.
- CID tracks down Mohan and arrests him after he kills two more people: Ramanan, a land grabber who cuts down trees, and Veer, a club owner who causes noise pollution.
Here are the key facts extracted from the text:
1. A blast occurred during a night patrol.
2. A constable was injured in the blast.
3. A suspect was seen escaping but disappeared suddenly.
4. A golden tooth with initials 'NK' was found at the blast site.
5. Naveen Kumar, identified by the initials 'NK', is missing.
6. Naveen Kumar owned a paint factory and was recently in the news.
7. His wife confirmed he had a golden tooth.
8. Naveen Kumar's death was confirmed to his wife.
9. Protesters against Naveen's factory claim they are social workers, not criminals.
10. The protesters were accused of threatening Naveen Kumar.
11. Evidence suggests someone with a severe skin disorder planted dynamite at the blast site.
12. The dynamite batch number led to a quarry where it was sold illegally for bomb-fishing.
13. The suspect with the skin disorder was not among those previously interrogated.
14. The investigation leads to a list of patients with a rare skin disorder.
15. The murderer used an environmental infection as a motive for the killings.
16. The murderer infiltrated the city's drainage system to escape detection.
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