I will have to recommend:
The proverbial "K&R". The C Programming Language. Many learned C from this book.
C Primer Plus is also a good book, but it's pretty long. If you have any experience whatsoever, you might be bored by this book.
C Unleashed. Not a beginner book, but a great book nonetheless. Many of the authors (Richard Heathfield, Lawrence Kirby, Ben Pfaff) are (or at least were years ago) very active in the newsgroup comp.lang.c. Their insightful, pragmatic posts were great, and so is the book
Good luck!