Restrict Access to Pages – Plugin Advice

We are looking for advice on a simple plugin that will show a password box in which the front end user needs to type the password in so they can view certain pages on the site. We do not want any type of registration or membership. Just a simple password box. The idea is that the password will be the same for everyone.

The content that they can access with the password is not highly confidential, it’s just that we don’t want the regular public to easily get to the content.