"Introduction to Moral Theology", by William Mattison, is a thoughtful, well written introduction to the topic. The author, an assistant professor at one of the Catholic universities, obviously knows his subject well. He is able to explain his topic well-he does not "dumb it down", but also does not make it too "academic" for the average reader.
Mattison approaches the topic from a "morality of happiness" approach, instead of a "morality of obligation" approach-we should pursue these virtues, not out some sense of obligation, but because, through them, we will become truly happy. He provides chapters on each of the seven virtues of temperance, prudence, justice, fortitude, faith, hope, and charity. He intersperses chapters on each of four "test cases", which examine how the virtues are best applied in real life. Finally, the author closes the book with an examination of how the virtues are embodied in the Our Father.
I would highly recommend this book to anyone interested in the topic of theology.