The Iron Hand of Mars is a 1992 historical mystery crime novel by Lindsey Davis and the fourth book of the Marcus Didius Falco Mysteries series. Set in Rome and Germania during AD 71, the novel stars Marcus Didius Falco, informer and imperial agent. The iron in the title refers to the standard, shaped like a giant hand made of iron, which Falco is required to deliver to the imperial legions in Germany. Plot summary Following the events of Venus in Copper, the Imperial authorities are seeking Falco out for an assignment in Germany (which given the events of his last mission abroad, Falco is slow to accept). Meanwhile, Falco is not pleased with Titus Caesar attempting to seduce Helena. When Helena gets an invitation to a private dinner with Titus, she pleads that Falco stay by her side on the same day, but he instead decides to see a client in Veii — who unfortunately turns out to be a widow more intent on pleasure than business. Disgusted, Falco returns to Rome, but Helena has disappeared, apparently leaving Falco for good. Romantically depressed, Falco goes over to the Palatine to be personally briefed by the emperor Vespasian on his latest assignment — broker peace between Rome and the Celtic tribes of Germany (whose leaders are thought to be Veleda, a priestess and Julius Civilis, a local strongman), locate a missing military officer named Munius Lupercus, and deliver a new standard in the form of a two-foot long human hand, cast in iron, to the 14th Gemina at Moguntiacum — the last actually being a pretext for Falco to investigate them, given that the 14th's loyalty is held in doubt. Much to Falco's annoyance, he is also to escort an ex-slave named Xanthus into Germany as well, whose specialty is hairdressing. Falco's trip is marked by a number of misadventures — poor food and even poorer wine, unscrupulous souvenir sellers and cramped conditions, as well as murder. At Lugdunum, Falco and Xanthus bump into two travellers quarrelling with a group of potters, who are later found murdered. At the crime scene, Falco makes the acquaintance of a centurion named Helvetius, before trying to contact Helena's brother Justinus, a military tribune serving at Argentoratum, but discovers that Justinus has been transferred elsewhere, and so proceeds down the Rhenus further into Germany, where the relatively wealthy Xanthus is accosted by a peddler