'Tune In: The Beatles: All These Years Vol. 1' by Mark Lewisohn
Never mind that epic, multivolume studies are generally reserved for stuff like the rise and fall of Rome: the Beatles were bound to get this sort of treatment at some point, so here's a chance to rock out at max length. Tune In runs 932 pages and ends before Please Please Me is in the can. We see, in glorious detail, how the Beatles lived in each other's pockets, fucked in front of each other, and forged an "us against the world" union.