Membership System

Hi,

I have been asked to create a private members database that can be access using a mobile phone, tablet or computer. I would like to use word press as I have a little bit of experience with it.

What i am wanting to do is as follows
1. A landing page with a little info about the company, offering a login to registered users. no option to register.
2. Only allow registered user access to the membership data

that the main idea, I have looked at a few plugins but none of them seem to be quite right for what I need. I will be honest and say that I have only looked at maybe 3 plugins.

I am using themify to do the design.

any help or pointers would be gratefully recieved.