Einstein's Theory A Rigorous Introduction for the Mathematically Untrained

From the reviews:

“Einstein’s Theory fits in an unusual place for introductory books on the topic. … this work reaches the mathematical, theoretical, and conceptual understanding of a graduate course, assuming just basic algebraic skills. … this is a rare book that can take the motivated reader with an elementary algebra background to a rigorous understanding of general relativity. Summing Up: Recommended. Lower-division undergraduates and general readers.” (E. Kincanon, Choice, Vol. 49 (9), May, 2012)

“This book stands apart from other introductory textbooks on general relativity in that it is aimed at non-science educated readers who nonetheless want to get a thorough understanding of this theory. … The book succeeds quite well in explaining the concepts underlying general relativity in elementary terms without sacrificing mathematical rigor. An additional bonus are the philosophical remarks obviously due to one of the authors being a philosopher himself.” (Helmut Rumpf, Zentralblatt MATH, Vol. 1234, 2012)