The Dam Busters by Paul Brickhill
This is one of the absolute classics about RAF Bomber Command in World War Two. It tells the story of 617 Squadron, formed for the 1943 Dams Raid. The run-up to and the Dams Raid itself take up about two fifths of the book and a thrilling tale it is, full of dramatic scenes.
The book goes on to follow 617 Squadron through the rest of the war, describing its raids on German submarine pens and the Tirpitz, its use of the massive 3-ton Tallboy and 10-ton Grand Slam bombs and much more besides. It is an exciting, dramatic tale.
This is a book of its time. First published in 1951, it contains no criticism of Guy Gibson. It is very much a story of "heroes" and some of the grimmer realities of life as a crew member in Bomber Command and questionmarks about the bombing campaign are glossed over. It is a very "masculine" account. But I think we shouldn't judge it harshly for this. All books are products of their time. You certainly want to supplement this account with later, more nuanced accounts of people like Gibson and cooler assessments of the impact of the Dams Raid and of the strategic bombing campaign.
But you shouldn't miss this account, written soon after the end of the war by someone who was himself a WW2 fighter pilot and, therefore, with considerable insight and knowledge. It is an excellent starting point and a true classic.