After my rather massive textbook Einstein Gravity in a Nutshell was published in 2013, my editor and I discussed the possibility of my writing a short book on gravity, filling the gap between popular books (such as An Old Man's Toy, aka Einstein's Universe) and textbooks. Our discussion resulted in this short book On Gravity in 2018. (Thus, you could understand my irritation at an ignorant customer review on Amazon complaining that this short book was not mathematical enough. Read my textbook instead!)
I designed this book for those readers who would like to understand what curved spacetime really means and could handle a few pages of college level mathematics (given in an appendix). After this, depending on your background, you might be able to move onto Einstein Gravity in a Nutshell.