Directory Permission question

We have a shared directory that is open to all staff. Everyone has full read/write privledges to everything there. We need to created a single sub folder with restricted access. 2 users will continue to have full read/write privledges to the restricted folder but I have been asked to create a third account for an admin assistant. This user will need to be able to create folders and documents in the restricted directory (they will be scanning documents and placing them in the various folders) but should not be able to open anything once it is written to a restricted folder.

Is this possible?

I have removed all inherited permissions and added the two privledged users without problem but have not come up with the correct formula for the third limited access user. It seems that a set of permissions that allow the user to both list and write a file also will allow them to read it again later. Any suggestions?