Company Forcing Employee To Work And Threatening Legal Action.

Hello, I am posting for a friend who is being harassesd by her employers. My friend has been working in a company in Noida, U.P., since the last 3 months. Upon joining the company, she was given an offer letter. She was made to sign an NDA, but wasn\'t given a copy of it, nor does she have the appointment letter or any salary slips. The salary was deposited straight to her account. Now, I\'ll tell you about the issue. The whole atmosphere of the office is extremely toxic. There\'s regular shouting matches going on, where the management puts extreme pressure on the employees. Almost daily, she has seen 2-3 employees crying out due to the bullying tactics applied on them by the management and HR. Non-HR personnel have been seen checking out live CCTV footages of the office on servers. My friend was sexually harassed by a new employee. And she immediately complained to the management, including the CEO and HR. Merely lip service was provided to her, with no concrete action of any kind. Her father was recently grievously ill, so she had to take 4 days leave, which were sanctioned. Upon returning, on salary day, she was told her salary was put on hold indefinitely. She somehow wiggled through the issue and got the salary released after a day or two. Due to the constant mental harassment, she doesn\'t want to continue working. Now after a few days, the office mailed her and asked her to come back & are threatning her with legal consequences if she doesn\'t reply or returns back. On the offer letter, it is written that one month\'s notice period has to be given to them before they leave. Also, the probation period is for 6 months. What to do. Should she reply to the mail. Or just continue to not go. Is it mandatory to serve the notice period. She dreads going back to that place, fearing torture.