If you're looking for a clean, legal PDF of a specific Arihant UPSC book, let me know the title and year — I can guide you to the official source or a better alternative (like Vision IAS or Rau's focus material).
It sounds like you're referring to the well-known "long story" behind — specifically, how their PDFs became widely circulated, and the associated copyright and quality issues. arihant upsc pdf
Here’s the concise version of that "long story": If you're looking for a clean, legal PDF