Actually even the movie rokkkk was good than shaapit, shaapit seems to be really shaapit with no story and no link at all, there is absolutely no link between what is happening.
As per the story, aman , kaya and pashupathi are set out to defeat the spirit of the pandits daughter, who is protecting the shrap given by the pandit some 350 years ago, because that was initially haunting the family. But in the end they end up fighting and conquering mohini the wife of the king, this has absolutely no relevance to the story shown in the begining, it has no link with the death of the pandits daughter and the shraap. It would make sense if they would have pacified the aaatma of pandits daughter because she is one who was doing all this, and supposed to have done all this.
Pashupathi is supposed to be a professor but as story moves on he seems to be such expert, in magic and occult science, really, transcribes ghosts languages, goes back in time without a time machine, in a jiffy just by uttering some mantras, it seems so easy, seems they just had to drag the story.
Rest story is all bakwaas.