davelgil: Hi - game developer here. To answer your question, yes and no. I made sure each Blackwell game had a stand-alone story, so you'll never be greeted with a "To Be Continued" at the end of a game. But at the same time, there is an overarching storyline that is being told with each installment. To put it simply, each game has a ghost/case that the characters need to solve and they each get resolved at the end. But the Big Story of who Rosa is and the world she inhabits is slowly evolving over the course of the series. So... make of that what you will.

edit: Oh, and yes there will be a fifth and sixth game. Working on the fifth right now, in fact!