In this short volume, Professor Richard P. Feynman delves into Einstein's special relativity. That's a very entertaining and scintillating book that i would advise anyone to read!

Chapter 3 is dedicated to a general introduction to special Relativity and to Lorentz transformations

Chapter 4 introduces the notion of relativistic energy

Chapter 5 describes the spacetime notion

And finally Chapter 6 takes the curvature of spacetime as principal study object.