It is AGAINST THE LAW for someone:

• To follow you around more than once, appear more than once at your home, work, or other place where you are, in a way which would make a reasonable person afraid.
• To intimidate you by causing substantial emotional distress or threaten you with death or bodily injury
• To follow you around even once, or show up at your home, work, or other place described in a protective order or bail order against him/her

If you think someone is doing any of the above things to you, call the police right away. The police may arrest (they may arrest without a warrant if the events happened within the past 12 hours). If there is a protective order in place, the police shall arrest. The police can make an arrest even if they did not see the person follow, threaten, or intimidate you.

Source: New Hampshire Legal Assistance