How to delete all files recursively but only from folders of a particular name?

I have a folder structure as follows:

Content+
       +-Guide 1-+-file1.html
       |         +-Markdown+-file2.html
       |                   +-file2.md
       |  
       +-Guide 2-+-file1.html
                 +-Markdown+-file2.html
                           +-file2.md

Essentially I want to run a single command to delete the contents of each Markdown folder for any such tree, but leaving other files as they are.

del /s /q Content*Markdown*.*

gives me:

The filename, directory name, or volume label syntax is incorrect.

Would appreciate the correct syntax if it is possible.