At the end of Ballistic, we saw that a missile with a nuclear warhead was launched from space against a planetary city. No warning was issued. A massive skyscraper is standing as a structurally unsound skeleton, and many thousands of people have died. CITADEL was always going to contain emotionally challenging scenes, but this is Marko Kloos’s pandemic novel. Expect it to be a tough read.

Palladium Wars is the title of the series, and the reference to the rare and precious metal is because starships need palladium to run computations. From engines to gunnery to AI, the more palladium built into it, the more expensive, and better class, the vehicle. Commander Dunstan Park of the Rhodian navy was on his way to his home port and retirement, in Ballistic, but the outbreak of hostility put paid to that. He’s quietly given command of a prototype ship packed with palladium, guns and a small crew. The arms race is on again.

On planet Gretia, Idina Chaudhary was getting along just fine with the natives when some rebels decided to stage an uprising. Sporadic violence means her soldier’s leave is cancelled. Now she’s on the street, armed and armoured, protecting bigwigs and getting shot at in the open.

Ship’s crewman Aden Jansen used a false identity. He’s not getting off lightly, and nor are his friends. His sister, Solveig, is the business heir since Aden walked away, but wealth now equals being a target. Solveig’s story is probably the hardest to read because it is most relatable to modern life. The lightest and most familiar Marko Kloos sci-fi is actually the nifty smuggling yacht with Aden aboard, hunting for the nuclear-armed ship that can outrun massive cruisers, and hoping to lead Dunstan’s vessel to fire upon it. That part was fun, a bit of astrophysics and piracy to lighten the weight.

If you have read the series to date, you will pick up easily, but if you have not, it might be difficult to get into all the narratives. CITADEL is a grand space opera and planetside chaos all at once, with an extremely high body count and several distressing scenes. The series continues with Descent.