The end of the month is usually an exciting time for most people with a PS4 or an Xbox One as next months free games start getting announced.
While Sony hasn't made an official announcement yet about which games will be free for Playstation Plus in December, the games may have been leaked if this post from Reddit's /r/PlaystationPlus is to be believed. If the leak is true it looks like Invisible Inc and Stories: The Path of Destinies are going to be two of the games that will be free for the month of December.
Now obviously it says "November games" but my guess would be that's probably a placeholder until the announcement is made and it's changed to December. Again, nothing official as of yet so take this with a grain of salt.
On a personal note, if this is true, it looks like Microsoft and Games With Gold blows away Playstation Plus' offering once again.