When Greek-Australian photographer Isaac Raftis, the protagonist in Tony Krawitz’s adaptation of Christos Tsiolkas’ novel, announces a trip to Europe to train a lens on his family’s long-abandoned homeland, he’s submitted to hostile testing. What’s the Greek, his father demands, for “eye”, “nose”, “mouth”? When Isaac slips up on the word for “hair”, it seems portentous: he’s headed for an ugly initiation into the Old World.

Played by Ewen Leslie – not always convincing here as a questing Greek, but great as a liberal with an eye out for cock – Isaac is a loving young man, but his father, Vassily (William Zappa), has left his mark. A postwar migrant to Sydney, Vassily dies suddenly, in the same way he’s lived: violently, with so much left unexplained.

Intent on good deeds, Isaac takes his father’s ashes “home”. Like some evil genie released, Vassily’s bone dust, shaken loose over a mountain gorge behind Athens with all the ceremony one might bring to the emptying of a vacuum cleaner, causes nothing but horror and suffering for the son. When garlic, an evil-eye amulet and a crucifix are pushed on him by relatives, Isaac, despite his robust Australian agnosticism, is brought undone by paranoia, and what seems to be an intergenerational curse.

Returning members of a diaspora certainly tread a difficult road and Dead Europe, when it approaches clarity on that subject, looks exciting and feels promising. Isaac’s passage into his father’s past winds not only through Athens, Paris and Budapest – physical places with reassuringly recognisable landmarks – but also more opaque, feverish scenarios: a Jewish-run child-porn racket hosted in a Hungarian nightclub dungeon; a middle-class Parisian apartment in which a polite dinner party devolves into grotesque physical abuse; spacey encounters with a teenage refugee (Kodi Smit-McPhee), fleeing we know not what.

Dead Europe’s gruelling travelogue riffs on Europe’s anti-Semitic history, Islamophobia, human trafficking, the brutal treatment of postcolonial immigrant populations – complex enough matters as discrete concerns but which, patched together, resemble an ill-fitting jigsaw.

More’s the pity, because there’s an early scene that is pure class. In an Athens lounge-room, Isaac, fidgeting on a couch, casually fields questions from his wealthy, urbane cousins about life as a gay Australian. “Do you have a boyfriend?” a young Athenian asks. “No, I just have lots of random sex with strangers,” Isaac replies matter-of-factly. The scene is moodily expressive, aerated with wit, dramatically alive. It shows how brilliantly attuned Krawitz can be, and how intuitive and gutsy these actors are when the script relaxes its sordid, polemical obligations.