One Site as a part of Multisite to be hidden (Un-published) from Public?

Lets say i have some sub-domains under one single Multi-site:

• http://ift.tt/1Cln8gx


• http://ift.tt/1BfmWv7 <---- hide from public access (Protected)


• http://ift.tt/1Clna84

How do i HIDE the one site only, from the public access.

(or) Put the site as something like Unpublished (or) dark site?

Any plugin or approach please?

Thank you so much.