'Poseidon's Gold', book 5 in the Marcus Didius Falco ancient Rome detective series, finally fills in the backstory of Falco's dead brother, Festus, Roman war hero and legendary talented older brother. We readers have been given to understand from the previous books Festus was the best and brightest sibling of the Didius family, and his early death during the Roman war in Judea has continued to darken the family's normal high spirits and energies.

Another thread throughout the books has been Falco's extreme hatred of his father, now a wealthy auctioneer. Geminus (Marcus Didius Favonius) walked out on the family of seven children and wife when Falco was a little boy, which brought painful starvation and poverty to the family for a time, although currently all of the children have grown up. Most of them got married and now have families of their own. Meanwhile, Geminus remarried and became wealthy in selling household goods and art.

A soldier, T. Censorinus Macer, who served under Festus, turns up claiming Festus stole money from the Fifteenth Legion in a scheme to upsale Greek statuary. The ship the goods were on sank while sailing to Rome, but the soldier claimed that was a lie. Censorinus thinks Festus sold the art and kept the money, and that the Didius family knows where it is. Festus died three years ago, and if he had stolen any money, the secret of where it could have been hidden, IF it had been stolen, died with him.

Falco is angry and does not believe the story - but, maybe Festus did it. Festus always did have schemes going on to make money, after all, although as far as the family knows, he would have never done something this underhanded. Maybe. People do change. Anyway, after he tries to question Censorinus further in a nearby bar, the two men get into a fist fight, witnessed by many other customers. Falco goes home, thoughtful and disturbed.

As the next day dawns, Falco discovers to his shock he is being sought by the authorities for the murder of Censorinus! Plus, the family's sense of personal honor and their memories of a favorite boy will be seriously harmed if the story of Festus cheating his fellow soldiers is true. As Falco begins to investigate Censorinus' murder one step ahead of the Rome police, he learns his father is being threatened by a pair of art dealers claiming they had prepaid Festus for a valuable art work on the ship which had sunk.

Calamity upon calamity! Will Falco discover the truth before he is scheduled to be strangled for murder and theft?

I recommend reading this series in order.