Messenger of Truth. A Maisie Dobbs Mystery
Nick Bassington-Hope, a controversial artist who gets inspiration from those around him is found dead when hanging his latest exhibition. The police believe it's an accident but his twin sister doesn't believe it and engages Masie Dobbs to investigate. She discovers that Nick's wartime experience has coloured his paintings and that some of his topics have made enemies of him. There's also some issues with smuggling that ends up being interwoven into the plot.
I did guess one of the plot twists fairly early on, but it's the finding out the motives of various characters and the ongoing seeing how Maisie develops held my interest