Things appear to be going well for cello-playing music student Jessica and her teacher boyfriend Lorenz when they move into their spacious new apartment. It's a great place, too, located in one of those old buildings where the ceilings are too high to reach even if you jump and whose living room is big enough to host a debutant ball in. The celebratory noise made on their first night there prompts a complaint from their upstairs neighbour, the middle-aged Hilde Domweber. Lorenz profusely apologises and the next morning Jessica knocks on their door to second his words. Hilde is understanding and even gives Jessica a moving-in present, a cherubic angel statue which Jessica politely accepts in spite of object's ugliness.

When Jessica is nominated to represent her country in an international competition she is understandably excited, but is aware of the pressure this is likely to put her under. All seems fine until she arrives home from a recital to find a sizeable pile of faeces on her doormat. Who could be responsible, particularly as the only animal in the building appears to be their tiny kitten Pikachu, which would be physically incapable of creating such a large deposit? Then again, when Jessica was taking out the trash the day before she almost collided with Hilde, who was outside her door and acting almost as if she'd be caught doing something naughty. And when Jessica sits and practices on her noiseless electric cello, she repeatedly sees Hilde staring down from her kitchen window above. Could she be behind this? But what would be her motive? One thing Jessica does right when she makes this unpleasant discovery – something that still fails to occur to other film characters in her position – is take a picture of the deposit before she washes it off the mat so that her loving boyfriend can't brush it off as her imagination or an exaggeration of the truth. Not yet, at least.

It doesn't end there. One day Jessica's doorbell is repeatedly rung but when she answers the door there's nobody in sight, and late at night she is woken by what sounds like light hammering that appears to be coming from the apartment above. Increasingly stressed out, her music begins to suffer, and matters are made worse by some casual sniping about her financial dependency by her father when her parents drop round for a meal. A night out with friends does wonders for her mood and prompts her to deliver her most passionate recital yet, but when their kitten disappears and Jessica discovers its collar in Hilde and her friendly husband Helmut's flat, her sanity begins to slowly unravel.

The LFF write-up compared Homesick to the early work of Roman Polanski and I can't help but suspect that this claim is partly inspired by the similarity of this film's setup to that of Rosemary's Baby. Both stories revolve around a young couple who move into an apartment block and whose neighbours include an older couple who at first seem to be friendly but who later appear to have sinister intentions. Like the titular Rosemary, Jessica also falls victim to justifiable paranoia and has her fears dismissed by her initially sympathetic but increasingly impatient partner, a too-common trait in male companions in such films that does prove to have some logical foundation here. Where Homesick does differ significantly from Polanski's film is that Jessica is not pregnant and Lorenz doesn't appear to be climbing the career ladder as the result of some Faustian deal, ruling him out as a co-conspirator and steering us away from a satanic explanation.

And for this particular viewer, therein lies the problem. As Jessica's growing conviction that she is being tormented by Hilde starts to negatively affect her mental stability, I began to suspect that all was just as it seemed after all and that the big twist that the story seemed to be building to was that there wasn't actually going to be a twist after all. Partly as a result, I'd worked out what was going on some time before the film delivered it's would-be 'gotcha' surprise ending.

Which is a bit of shame, as the journey to this point is layered with intrigue and peppered with genuinely unsettling sequences. There's a compellingly steely quality to third-time feature director Jakob M. Erwa's observational approach, one humanised by Esther Maria Pietsch's thoroughly convincing performance as Jessica. It's the bond I formed with her that kept me in her corner for a good portion of the story, one that seriously faltered once it dawned on me what the issue really was. I was left with a sense that a film which had done such a good job of hooking me and holding my attention for so long ultimately bailed on me in its final third by building expectations on which it had never had any plans to deliver.