Cat and Mouse is the book Gunter Grass wrote immediately after The Tin Drum and shares this book’s setting of Danzig during WWII.
The narrator is a boy / youth / young man called Pilenz who is besotted with the ‘hero’ of the book Joachim Mahlke, who has a prominent Adam’s Apple and a prominent appendage. The former attracts a cat who believes it to be a mouse (hence the title) and the latter attracts Mahlke’s commander’s wife, even though Mahlke is supposedly devoutly religious. Well, I’m not sure either of these two storylines are too believable, but I moved on.
A lot of the time, especially in the first part of the book, is spent swimming to, sitting on, and diving around a sunken Polish minesweeper Rybitwa that becomes a second home for Mahlke. The relationships between the two boys and their friends are well described before Mahlke leaves to become a highly successful tank commander on the Eastern front. Pilenz remains around Danzig but Mahlke returns at the end of the book.