The Frankfurt Holocaust trials of 1963-65 are nowhere near as well known as the Nuremberg war crimes tribunal, but in a very real sense they were more important to the post-war rehabilitation of Germany, and the background to them is presented earnestly, if a little loosely, by Giulio Ricciarelli in “Labyrinth of Lies.” The film, which mixes fact with fiction, is an honorable if sometimes melodramatically facile attempt to portray a watershed moment in modern German history.

It begins in 1958, when idealistic, ambitious lawyer Johann Radmann (Alexander Fehling) begins working at the public prosecutor’s office in Frankfurt. Irritated by the trivial cases he’s assigned—traffic infractions and the like—he undergoes something of an epiphany when he meets Thomas Gneilka (Andre Szymanski), a pushy journalist trying to get the office to act on the complaint of his friend Simon Kirsch (Johannes Krisch), a Holocaust survivor who has accidentally encountered a former Auschwitz guard now working as a teacher—a position he should not, under the law, be allowed to hold.

Radmann, like so many his age in West Germany, doesn’t even know of Auschwitz or the other camps; brought up in what amounts to a conspiracy of silence about the atrocities committed during the war—and in a society that tolerates, and in some cases positively encourages, the quiet acceptance of ex-Nazis in ordinary life, he’s ignorant of the realities of the Final Solution. But unlike his colleagues—who brush off Gneilka with ridicule or contempt—he takes the newspaperman seriously, meets Kirsch, and eventually comes to a growing recognition of the horrors perpetrated by the wartime regime and the need for the law to act against those who participated in them. His diligence is noticed by the district’s Attorney General Fritz Bauer (Gert Voss), a Jew who spent the war in Sweden, and he assigns the young man the task of prosecuting a case against the ordinary war criminals who are now hiding, as it were, in plain sight. He must overcome obstacles put in his way by the bureaucracy, and eventually overcome a personal crisis of conscience, to do the job and bring the guilty to justice, forcing the German populace as a whole to come to terms with the Nazi legacy.

In crafting the script, Ricciarelli and his co-writer Elisabeth Bartel have taken substantial liberties and added some very formulaic elements. Radmann is actually a composite character standing in for three prosecutors actually involved in the case (and, of course, he’s actually standing in for a whole generation of Germans ignorant about the genocide). His naivete can appear incredible at times. Moreover, he’s given a romantic subplot—a relationship with a young girl he meets “cute” when he prosecutes her on a traffic violation and pays her fine when she can’t—that comes across as the stuff of fifties comedy. A thread involving his obsession with tracking down Josef Mengele leads down paths (including too many nightmare sequences ending with him waking up in a sweat) that of course go nowhere. And it’s almost inevitable that his researches will produce revelations about his girlfriend’s father—and his own—that will cause him to question how much good, if any, he can do—and, of course, threatens their relationship. (This last-act bout of despair, which even includes his briefly taking a job with a wealthy litigator whose motives are clearly not pure, comes across as a dramatic contrivance out of screenwriting 1-A.) Even a visit to Auschwitz with Thomas, during which the journalist reveals why he’s so dedicated to the cause of publicizing what happened there to the world, feels a forced effort to check off all the manipulative blanks.

But if “Labyrinth of Lies” often devolves into the sort of earnest polemic that marked many American films of the fifties and sixties, the subject matter is so inherently powerful that it remains a worthy and moving effort. Though as the handsome but rather bland Fehling portrays him Radmann may sometimes comes across like the screenwriting device he actually is, one can discern the depth of authentic emotion involved in the pursuit of justice in the person of Bauer, whose quiet demeanor cloaks a passionately personal drive to bring the criminals to the bar as he instructs his subordinate to avoid going off on tangents and keep his eye on the prize. He’s played to perfection by Voss, who brings a sense of almost unimaginable melancholy to the reserved, world-weary character. The remaining performances are solid but unexceptional, with Szymanski sometimes coming on too strong but Hansi Jochmann exuding motherly pain as the elderly secretary who’s shocked by the testimony camp survivors give. (The details are treated with restraint and decorum, with the witnesses’ words presented in a montage dominated by the mournful music of Niki Reiser and Sebastian Pille. That’s a defensible directorial decision, since presumably every viewer will be able to fill in the awful descriptions themselves.) Friederike Becht is attractive as Marlene, Radmann’s girlfriend, though in truth she’s not asked to do anything demanding. The technical side of the film is strong, with Martin Langer and Roman Osin contributing luminous widescreen cinematography and Manfred Doering an elegant production design (his recreation of the US Army Document Center, overflowing with files, is especially impressive).

Incidentally, the original German title—which would translate as “In the Labyrinth of Silence”—is more resonant than the English version, pointing not only to the maze of obfuscation that Radmann must penetrate but to the reality of Auschwitz, where so many perished, unable to tell what happened to them there.