内幕 (nèi mù): inside story; non-public information; behind the scenes; internal

A journalist spent half a year investigating that company's financial problems and finally exposed little-known inside information in the newspaper.

He used to work at this club, so he knows quite a lot of inside information, but he has never dared to tell outsiders.

After the match ended, the referee admitted he had taken money, and only then did everyone learn the inside story behind the game.

That documentary is about the inside story of a food factory; after watching it, many viewers no longer dare to buy that kind of snack.

In her book she wrote about her own experiences as an actress, revealing to readers quite a lot of inside stories from the film industry.