The Lady in the Lake, by Raymond Chandler

Marlowe does his thing, while Chandler does his. Both of them are smart and keep secrets, and don't give away much. But I cottoned on to the whodunit part pretty early, but it's still an enjoyable ride through hardboiled Los Angeles. An interesting detail as he's heading out to a dam is that, during wartime, soldiers were stationed on the dam and asked drivers to roll up their windows, presumably to prevent people from sabotaging the water supply. And hard not to like a meta-discussion of villain monologuing.

'I've never liked this scene,' [Marlowe] said. 'Detective confronts murderer. Murderer produces gun, points same at detective. Murderer tells detective the whole sad story, with the idea of shooting him at the end of it. Thus wasting a lot of valuable time, even if in the end murderer did shoot detective. Only murderer never does. Something always happens to prevent it. The gods don't like this scene either. They always manage to spoil it.'

'But this time,' she said softly and got up and moved towards me softly across the carpet, 'suppose we make it a little different. Suppose I don't tell you anything and nothing happens and I do shoot you?'

'I still wouldn't like the scene,' I said.