Stephen Fry and Lena Dunham play a Jewish father and daughter who miscommunicate their way through 90s Poland, until a visit to Auschwitz allows them to dig up the past (literally). There’s no doubting the good intentions of Dunham, Fry and the esteemed German director/writer, Julia von Heinz. All three clearly want to use this adaptation of Lily Brett’s novel Too Many Men to explore survivor’s guilt and enduring antisemitism. Alas, most of the film’s big scenes are either tonally muddled or soul-crushingly predictable.

Fry, who learned Polish to play Edek Rothwax, is miscast as an honorary New Yorker whose avuncular persona masks fear and fury. We believe in the character’s charm and suppressed pain (Fry is pitch-perfect in the chilling segment of the movie in which Edek visits his requisitioned family home). What he can’t convey is Edek’s Big Apple attitude or rage. As for Dunham, her Ruth – sometimes abject, frequently abrasive – is a potentially fascinating figure who’s been overloaded with distracting problems. This music journalist has a chronic eating disorder, engages in a grungy tattoo ritual and secretly obsesses over an ex called Garth. Every time Garth’s name was mentioned, I groaned. The truth about Treasure: it’s too conventional to satisfy devotees of Lena Dunham and too much of a vehicle for Dunham to please anyone else.

• In UK and Irish cinemas now