Behind the Mask opens up when Arjun Dev, an author of book 'Breathing symbol,' receives a frightening midnight call from his mentor, Mr Adyapak. Unfortunately, unforeseen circumstances force Arjun to escape from his apartment along with his cousin brother Sachin and rush towards Hampi in search of his mentor.

An unknown criminal uses Arjun as a toy, blackmailing in the name of Sachin.

The story takes a twist when Arjun receives a piece of paper. The paper reveals about the 'Fibonacci series.' The author starts chasing the clue to find the source for all the unforeseen circumstances. His in-depth knowledge about mathematics and mythology leads him to reveal the game plan and the purpose of criminal. But, will he be able to solve it?

Finally, the question is, who wins the race with their perfect plan. After knowing the truth, it's an another mystery