This 2014 book Beethoven: Anguish and Triumph by composer and music critic Jan Stafford reward the patient reader.
At 1077 pages it’s the definitive biography. It also covers a lot of the music. This will require some musical know-how to fully understand some parts of this book.
It is thus best to read this book after reading Beethoven’s The Man Revealed by John Suchet if you are not from a classical music background.