In my metaphysics class, we used the book "The One and the Many" by W. Norris Clark. It isn't pure Thomistic metaphysics (it's actually based on Lonergan's Transcendental Thomism), but it isn't a bad starter.
Thanks a bunch—GGG
Speaking of St. Thomas Aquinas...
“The truth of our faith becomes a matter of ridicule among the infidels if any Christian, not gifted with the necessary scientific learning, presents as dogma what scientific scrutiny shows to be false.”
Saint Thomas Aquinas