IS there any subject that should not be joked about? It is a question that Taika Waititi’s comedy drama begs from the start.

At first glance, Jojo Rabbit looks as if it stands a fair chance of confounding expectations. In its favour, this tale of a German boy whose imaginary friend is Hitler stems from the bestselling novel, Caging Skies, by Christine Leunens.

It stars Scarlett Johansson as the boy’s mother, Rosie, who is hiding a Jewish girl from the Nazis, and Sam Rockwell as a German officer busted down the ranks for past insubordination.

Moreover, it is directed by Taika Waititi (What We Do in the Shadows, Flight of the Conchords), one of a number of filmmakers from New Zealand known for their gentle, absurdist humour.

Waititi opens the tale with Jojo (Roman Griffin Davis) going off to a Hitler Youth weekend, complete with book burning. The war is being lost, Captain Klenzendorf (Rockwell), the officer in charge of the event, is permanently sloshed and disillusioned. As a test of Jojo’s toughness, he is told to wring a rabbit’s neck. When he refuses he is given the nickname of the title.

The story is told from the point of view of ten-year-old Jojo, with Waititi relying on the viewer to join the dots, much as the boy himself does after discovering he and his mother are not alone in the house. The advice from “Hitler” is clear, turn in Elsa (Thomasin McKenzie), but Jojo dares to think for himself.

Waititi takes the Hitler role, playing the character as a buffoon. The comedy in general is off the wall, one scene more absurd than the next. Every now and then, the film will try to draw the viewer up sharp with a reminder of the real horrors of the time.

There is no doubting that the hearts of all concerned are in the right place, and there are one or two nicely crafted moments. The scenes between Jojo and his friend Yorki (Archie Yates), are sweet and joyful.

But on the whole the film is too often strange and unsettling. For very long stretches it is difficult to smile, let alone laugh, at the goings on.

It is not that Hitler should be out of bounds. Think of The Producers. Two impresarios, seeking to make some crooked bucks, stage a musical in such shocking taste it is bound to flop. Instead, after the audience’s initial shock – one of the great cutaway scenes of all times – Springtime for Hitler is a smash.

Brooks’s film is funny, and viciously so. It gives absolutely no quarter in its eagerness to mock. Jojo Rabbit, in contrast, tries for whimsy where there simply is no place for it.