Of course one of the reasons to watch this film (if you’re a man) is to catch Sydney Sweeney at a point in her career when Hollywood realised how sexy she was and cast her in a lead role but where her cachet and box office hadn’t given her the clout to refuse roles that traded on her beauty and sexuality.

Like seeing a particularly attractive female pornstar in an adult movie, one of the reasons you keep watching is the promise of seeing her undressed and/or in flagrante.

Thankfully it’s more polished and a lot more stylish than that, with writer/director Michael Mohan taking the filmmaking crafts more seriously and taking more care than the premise and plot sometimes warrants.

Pippa (Sweeney) and her boyfriend Thomas (Justice Smith) have just moved in together in a Montreal CBD apartment and are looking forward to enjoying the freedom, togetherness and responsibility of being proper grown-ups.

They’re barely there a single day when they notice the couple in the apartment across the street, an attractive and adventurous pair who make love in full view of the outside, a sight Pippa and Thomas witness and somewhat enjoy tinged with guilt.

The pair hatch a plan to listen in on the pair as well as watch them, using the opportunity to crash their lavish Halloween party to plant a device that will help them eavesdrop from the comfort of their place thanks to a laser pointer.

Pippa grows more fascinated and soon concerned about the pair, especially when she sees the man – a fashion photographer – banging every model he has at the home studio while his partner is out.

She becomes determined to expose him, while Thomas exhorts her to keep her nose out. But unbeknown to him, Pippa has also started fantasising about the man, who appears to be a much more accomplished lover than Thomas is.

When the woman, Julia (Natasha Liu Bordizzo), gets an exam for new glasses at the optician where Pippa works, the latter realises who she is, but Julia is so friendly the pair find themselves bonding, making plans to hang out.

As she befriends his wife, Pippa becomes determined to blow the lid on the man’s infidelities, figuring out how to hack their printer wirelessly and send anonymous messages to Julia while she’s home that prove her husband’s cheating.

It sparks a huge fight with Thomas, after which Pippa promises to try and stop. But as soon as they make peace with the decision, they look across the way to find Julia has apparently killed herself in grief. Thomas, unable to live with the guilt, blames Pippa and promptly leaves, breaking up with her.

From there it gets very, very pulpy – a tale of sex, deception, suicide and murder. Pippa, her life in tatters, finds herself drawn closer to the man, now revealed as the charismatic but possible dangerous Sebastian (Ben Hardy), and doesn’t know which way to turn.

But despite descending into melodramatic trash (an assignation of fact about the trashy genre, not a criticism of the tone, which it establishes beautifully and never breaks), there’s a lot to like about some very realistic touches.

The laser pointer and mirror set piece to listen in on Sebastian and Julia is just a MacGuffin to make the story happen, but Mohan makes it seem entirely plausible both by the hoops Pippa and Thomas have to go through to set it up and how it eventually works.

And even though when Pippa and Sebastian finally end up in bed together – the couch, actually – it’s a very gilded and photogenic (as well as very hot) sex scene, it treats the sex life she has with Thomas far more relatably in two young people who haven’t found their true sync points as sex partners yet, leaving Pippa unfulfilled enough to have a roving eye.

Every frame looks great, from the evocative locations to the deft camerawork that depicts the life of the couple across the street, the actors are all in (though Hardy is a little bit overzealous) and the quality belies how lurid and garish the story is.

But if you’ve seen Sweeney in later roles and fantasised about seeing much more of her, look no further.