I've a feeling you're not going to like this answer...
Traditionally UFRaw has been the "plug-in" for processing RAW files, BUT it's essentially a stand-alone application that has fairly good integration with GIMP (It knows how to pass images directly into GIMP once RAW processing is complete)
You need to know that GIMP is still only processing images in 8-bit colour depth, so you are advised to do as much as you can with your RAW processor of choice before importing into GIMP.
There is ongoing development to move GIMP to high bit depth processing, but no time scales are available as to when this will be completed.
Currently UFRaw is suffering some neglect when it comes to a Windows version and other alternatives are available, Photivo & Darktable to name two.