Looking for book recommendation: best book to start learning Powershell

I'm an application developer, a database developer, a 'fill in the blank' developer. I've tried a couple of times over the years to get into Powershell but ran out of time and energy before I got to the point where I could use it effectively. I've got a couple of ideas for how I'd like to use Powershell now (and I know I'd find more once I became comfortable with it).

I'm looking for a recommendation on a book that would gently guide me into Powershell.

thanks!