While the original "Ssshhhh...Koi Hai" started as an anthology of ghost stories before shifting to the Vikraal-Gabroo format, attempted to recapture that magic with a fresh narrative approach.
The phrase in question seems to be a of Shhh...Phir Koi Hai and the word nishaan (from certain episodes where a footprint or mark was the clue). Purists might say it’s grammatically odd — "nishaan" doesn't naturally follow "koi hai" — but horror grammar follows mood, not syntax. ssshhh phir koi hai nishaan
