Tweedy British sound designer Gilderoy (Jones) travels to the notorious Italian studio to mix the audio for The Equestrian Vortex, a 1970s bloodbath about nuns suspected of witchcraft. Director Santini (Mancino) insists that this is a serious historical drama, but the voice actors and sound artists all recognise it as a trashy romp. But as Gilderoy struggles to get reimbursed for his expenses, other things start to twist and turn. And then the gruesome movie starts to merge with his private life.

Intriguingly, Strickland only shows us the film within a film's gaudy title sequence, evoking the rest of it through a wonderfully detailed sound mix as the audio track is being assembled. This is often wickedly hilarious, with screaming actresses, outrageous dialog and smashing fruit and vegetables to get the right noises. It's also an engaging, almost nostalgic look at analog sound assembly. Strickland shows this with an entertaining attention to detail, playing on the fact that a lot of skill goes into making even the worst movies.

The film is also finely tuned to the Italian culture of jagged humour and macho womanising. Here, Gilderoy is like a fish out of water (he still lives with his mum), and Jones plays him to perfection, especially as we see his grip on reality eroded by everything that happens around him. His interaction with the other cast members is packed with insinuation, and Strickland shoots and edits with a lush fluidity that lets us follow Gilderoy down into the rabbit hole.

With such a range of vivid sights and sounds, the film is a stunning, often mesmerising experience. As events turn increasingly surreal and dark, it also becomes more and more horrific, leading to a transcendent moment of filmmaking genius. Alas, it doesn't end here, and there's a swirling coda that stops the forward - or rather downward - momentum in its tracks. Clearly, this is Strickland's point, but it leaves us slightly unsatisfied at the end.

British explorer Jonathan (Dillane) is leading a crack team of scientists into deepest Congo to verify reports of the mythical "mokele mbembe", Africa's answer to the Loch Ness monster. Jonathan's team includes ambitious right-hand man Charlie (Brooke), medical doctor Liz (Loring), local guide Amara (Ayivor) and two clucklehead cameramen (Weideman and Jennings). There's also a stowaway: Jonathan's 15-year-old whiz-kid son Luke (Kane), who has just been thrown out of school for doing something rather hilarious. When their helicopter crashes in the jungle, what they find is much wilder than they could have imagined.

It's handy that this comical TV crew is along to capture the chaos, because that means the stunning landscapes (it was filmed in South Africa) are shot in glorious high-definition. Although Luke's lapel-cams seem to have even better quality, plus the ability to withstand encounters with rocks, water and wildlife. Not that anything in this film makes much logical sense. But the filmmakers merrily charge through the story in such a breathless, energetic way that we don't really have time to pick it apart until afterwards.

In other words, this is a rare found-footage movie that's fast-paced and packed with action. And there are several sequences that are genuinely frightening along the way, from a jarring night-time encounter in an abandoned village to a freaky sea monster attack. As the effects work gets more involved (it's sometimes quite impressive) and the characters literally go down the rabbit hole into even more craziness, it starts to feel like they've wandered into the Land of the Lost.

In the end, it's the silly narrative that lets the film down, as the story's not-so-subtle subplots emerge into something that's overblown and distracting. Essentially it's bait-and-switch filmmaking, as the script reveals that the true danger here is bitter jealousy, strained father-son relationships and tampering with ancient tribal voodoo. In other words, the filmmakers clearly didn't think that discovering a world of living dinosaurs was nearly scary enough.

Peter and Lorna (Denham and Vicius) head off to a top-secret location where they are initiated into a cult led by Maggie (Marling), who claims to have travelled back from the year 2054. But Peter and Lorna have a secret: they're collecting material to debunk Maggie and her followers as a nutty apocalyptic cult. Then Maggie starts getting under their skin, as the cynical Peter finds himself wondering about the impact of his painful childhood and the addictive Lorna gets sucked in deeper than she expects.

Director Batmanglij shoots and edits like it's a lo-fi science fiction movie, with white walls and hospital gowns (to protect the Maggie's depleted immune system). The secret gatherings are in an over-lit windowless basement complete with a greenhouse to produce Maggie's food. Then one of Maggie's followers produces a pistol. And Maggie asks Peter to bring her a young girl (Pohl). And there's also a mysterious woman (McFadden) who seems to be on everyone's trail.

All of these things raise big issues that the filmmakers seem unable, or perhaps unwilling, to explore. Issues of child abuse echo loudly around the edges, implying the source of the characters' steel-edged fragility, but this idea is only ever used to make us question each person's motivation, not to drive the story forward. And while the time-travel subject matter has plenty of in-built intrigue, at least the filmmakers keep it alluringly out of reach as a plot point.

All of this gives director Batmanglij plenty to tease us with, as the connections between various characters twist and turn right to the abrupt final scene. The cast is terrific at layering in tiny quirks that maintain our scepticism, with Denham and Vicius especially effective at playing people who aren't quite sure who their partner is. Or who they are themselves. Opposite them, Marling comes across rather condescending and creepy, but then that's what gives the whole film a necessary jolt of uncomfortable energy.

In Birmingham, the Hare & Hounds pub is a struggling venue for new music. So manager Keith (O'Driscoll) stages a battle of the bands, failing to realise that sound man Russell (Mills) and barmaid Rosie (Waller) are potential performers. One of the aspiring bands is The Scholars, fronted by Adrian (Banks), who is so lost in trying to find success that he's neglecting his smart girlfriend Dillan (Pearce). And as the fateful night approaches, all of these people will need to learn to listen to others before they can make their voices heard.

The script came out of workshop sessions, Mike Leigh-style, which makes the characters feel organic. Especially since they're played with effortless skill by an attractive young ensemble that creates complex characters we enjoy watching. Most characters have a dark side, and yet they're never unlikeable since we can identify with their insecurities and bad decisions. O'Driscoll's tetchy-nasty Keith even has a vulnerability that catches us off guard. While the cast clown Mills gets a pay-off scene that's remarkably effective.

Unnecessary chapter titles suggest that the film is structured like a pop song, but it's actually following the rom-com formula. Thankfully, the multi-strand narrative subverts this, leaving us wondering how things will work out in the end and then surprising us with light-handed plot points. It's refreshing to see a film that never forces its characters into some sort of corny story-driven corner, but rather lets them discover their own path through the story.

And while this is essentially a comedy with romantic undertones, the film also says a lot about ambition and aspiration. Each character takes a journey to discover if what they want from life is worth pursuing, and the most important lesson is that they should never underestimate themselves or the people around them. While most of the plot strands are tied up in happy bows at the end, there are a few realistic loose ends to remind us that some of us haven't quite got there yet.