Just finished Frank Wilczek's excellent "The Lightness of Being". Wilczek got his Nobel Prize for his part in developing Chromodynamics, the theory of quarks and gluons and their strong force interaction. We get an awe-inspiring jaunt through the most modern views of the quantum vacuum (which W. calls "The Grid") and unification theories (including SUSY).
Lots of stuff I hadn't understood before - for example, the mass of protons and neutrons (actually hadrons in general) is not at all a primary attribute. Instead it's Nature's optimisation compromise between the energy in the colour field (decreases as quarks and antiquark, for example, get closer together) and the increasing energy of 'localisation' as the said quarks and antiquarks are constrained into the same place: (more precision in location means higher momentum and energy). This energy (E/c2) is what turns out to be the proton or neutron mass: the quarks and gluons themselves are almost massless.
Wilczek writes in a humorous and crystal clear way, which makes his book that rarity in popularisations - a bit of a page turner! Warning: you need to be comfortable with the conceptual basis of 'undergraduate' quantum mechanics and special relativity to engage with this book.