One recommendation, and one meta-recommendation:
The recommendation: Mr. Neighborly's Humble Little Ruby Book. Short (maybe 150 pages).
Meta-recommendation: Get a copy of Anki (free), and as you read, make new cards that test a single piece of knowledge (this can mean you make two or three cards for one concept...so be it!).
I highly recommend the pickaxe book (http://pragprog.com/book/ruby3/programming-ruby-1-9) for a full examination of Ruby and its standard libraries, as well as for a reference later on.
Sandy Metz's new book on advanced object oriented design in Ruby is amazing and a fun read (http://www.poodr.info/book/)
And Michael Hartl's online Rails tutorial is in my opinion the best place to learn Rails from beginning concepts to advanced strategies (http://ruby.railstutorial.org/)