This is a pretty niche subject, but as a biographer of Lewis Carroll I found it very well argued and researched, and most interesting. It explores whether Lewis Carroll ever actually visited the town of Llandudno, which makes a lot of its Alice in Wonderland connections. Actually Llandudno allowed the demolition quite recently of the house which the "real" Alice lived in, which was its only real link with Alice.... and with Lewis Carroll - if he ever stayed there.
So a nice little piece of detective work which kept me guessing till the end.