Amy and Bella - The Stalker Part 4 of 5

Bella is a private detective. Awaits a client. Before that, a man comes into her office. Bella is quickly overpowered and tied up. Then the stranger waits for the client. Amy is pursued by a stalker. In the event she will also be attacked by the stranger and tied up. Who is the stranger and what did he want to do with the two pretty young women?