Collecting lead with a pop-up form windows

Hello to everyone,
I’m looking for a plugin which it’ll appear when someone tries to read a post. The plugin is going to be a form (just a few information about the visitor) and when visitor enter the information she/he can read the article.

Just imagine you are on a website, and when you click to a title, a pop-up form window appears which is asking a few basic questions, and when you enter the info and apply, you will go to the article page which you wanted to read. It’s kind of premium/private content but I’m not looking for a plugin to charge anyone, just trying to collect some leads.

any suggestions??