The 'time travel trilogy' following Joe's adventures into Crystal Palace past should be read Star of Nimrod, Palace of Shadows and Palace of Flames. The action in Palace Above the Clouds is set between Star of Nimrod and Palace of Shadows when Joe is back in our time. It follows our favourite Victorian friends and there aren't any spoilers so you could read it in chronological order if you wanted Palace of Beasts is also set between Star of Nimrod and Palace of Shadows and could be read and enjoyed at any point - this novella is free for anyone signing up to my author newsletter.