What the muse wants...

I began work on a new manuscript a couple months ago.  I've plotted it out, written my outline, done my character sketches, assembled pictures for my picture board, even ordered the cover.  And now I'm almost at 10,000 wds but, in the last week or two, work has stalled.  My output is nowhere near the 1,000 wds. per day I usually aim for.  What, you wonder, is the problem?

Simple.  Earlier this year I started turning over an idea for a new story, a mystery that deals with some of the issues of human smuggling and drug trafficking with which the Caribbean struggles.  I collected articles, roved through countless reports put out by the United Nations Office on Drugs and Crime, and suchlike but I couldn't figure out the angle I wanted to take, who my characters would be or how the plot would unfold so I turned to the other story, a women's fiction.

Then, for some reason, the crime story began to come together a couple weeks ago.  In my free time I rifle through the articles I downloaded and watch YouTube clips of U.S. Customs intercepting traffickers.  Slowly, slowly, the story has taken form.  And, in the last few days, I've taken to waking up with it on my mind.  I know the names of the characters.  I know what they want.  I can see them. 

My instincts say I must drop the women's fiction, for now, at least, and work on the mystery instead.  It's the one my muse clearly wants written and if I don't get it down now, maybe it will all go wrong and when I finally turn to it, my muse will have weakened, maybe died altogether and the story will be a husk.  So far, I've resisted.  I power up the computer and begin working on the other story because it's the one I've already started and I must be disciplined.  But writing isn't like that, is it?  What the muse wants, the muse gets.  I think I'm going to have to try working on two manuscripts simultaneously.  This will be new to me but we'll see how it goes.  Any tips, anyone?