Yeah, and you already have it 
Calibre is the everything-from-anything ebook converter tool: Calibre - Conversion from Microsoft Word docs
Calibre’s default “drop and convert” is good enough for simpler docs, but it also has a crapton of powerful transformations if you need to more deeply customize how it converts a file… you can customize everything from fonts to chapters to headings to line breaks to embedded images etc.: Customizing Calibre conversion
Or you can try opening the Word doc in MS Word and re-saving it as HTML or RTF and see if that’s any better.