This engaging text takes the reader along the trail of light from Newton's particles to Einstein's relativity. Like the best detective stories, it presents clues and encourages the reader to draw conclusions before the answers are revealed. The first seven chapters cover the behavior of light, Newton's particle theory, waves and an electromagnetic wave theory of light, the photon, and wave-particle duality. Baierlein goes on to develop the special theory of relativity, showing how time dilation and length contraction are consequences of the two simple principles underlying the theory. An extensive chapter derives the equation E = mc2 clearly from first principles and then explores its consequences.