Ask HN: Which PHP Dev Book?

I have dabbled in PHP for a number of years, really just doing a tiny bit for one of my websites and then moving on, never investing much time in the language.

Now that has to change, I really need a book to sit down with that will teach me the core basics without over complicating things, and then allow me to move on to harder books.

Would also like to know if there are actual online study groups/classes where I can learn from my peers?