When James and Anthony (Ireland and Green) were children, a boy went missing in the river and James was charged with murder. Years later, there are still no answers. Now as James is released on parole, he gets some help from his mum (Fox), but has a secret goal to find the truth. Moving into the family's deserted mobile home, he befriends the curious young Damien (Grounds) next door. Then Anthony turns up to taunt him. But information from the local dog lady (Morse) and a friendly shop clerk (Robinson) helps James focus his investigation.

Filmmaker Scicluna keeps the tone almost unnervingly intimate, delving into James' internal thoughts as he grapples with both his past and his rather grim present. Details about what happened are elusive and disturbing, but slowly emerge through James' persistence. The subdued tension between all of the characters is vivid and explosive, especially as everyone is reluctant to dredge up the painful past. And as seen through James' eyes, the river takes on a personality all its own.

Performances are raw and complex. Both Ireland and Green create characters who are sympathetic but not always likeable. Ireland's open-hearted presence makes it quietly clear that James is a good guy who needs closure rather than revenge against Anthony for leaving him to carry the blame. Meanwhile, Green's performance is more difficult, an arrogant bully who is also fragile and damaged. Grounds is magnetic as a young loner caught in the middle of a situation he doesn't understand. And as the story continues, some real monsters reveal themselves.

The story is packed with unusually layered gay relationships, from tender companionship to more predatory interaction, all of which hints at much more complicated connections between James and Anthony. Scicluna controls each scene carefully, slowly increasing the conflict so that, when the deep-rooted feelings boil over in a series of climactic scenes, the emotional kick is very strong. It's not always easy to watch, but this is a provocative drama that gets under the skin and stays there.

To prepare for a Mars mission, company executive Walter (Bowler) hires four astronauts for a 400-day underground simulation. Captain Theo (Routh) is hungover after breaking up with medical officer Emily (Lotz), Dvorak (Cook) has a smart answer for everything, and Bug (Feldman) is a nerd with an overactive imagination. The programme starts well, with some wrinkles to test the team's mettle. Then after a week there's a massive shudder as all communications fail. Thinking this is part of the plan, the team continues, even with increasing hallucinations, stress and worries about what's happening above-ground.

Making a sci-fi thriller with no special effects is pretty daring, and Osterman inventively makes the "ship" look like a modified apartment with spacey design touches. He also nicely plays with the fact that this crew is increasingly unsure whether or not what's happening is part of the simulation. The obvious suspicion is that the world has ended and they're only surviving because their solar panels are still functioning. This doesn't explain other gaps in the premise, but never mind.

The actors are engaging, although each is far too unstable to be accepted into a programme involving isolated cooperation for more than a year. Tensions gurgle up between them at the expected moments, while their delusional visions provide plenty of red herrings. All of this is well-played by four actors who look increasingly lost (and perhaps a bit bored too) as the movie goes along. A mob of grubby townsfolk led by Cavanagh appears in the final act, as if they wandered in from the neighbouring set of The Walking Dead.

Annoyingly, none of this makes much sense. Osterman dribbles hints into every scene about where this might go, but he never actually gets things moving. Instead, the film seems to meander along in search of something that might drive the plot or a theme that might give this some meaning. Because it looks interesting, and there's a lot of promise in the set-up and the characters, the audience hangs in there right until it becomes obvious that, beneath the layers of mystery, this movie doesn't actually have anything to say.

Now working at a tampon sales company in Reading, David (Gervais) has cashed in his retirement funds to pay for a three-week road trip with his band Foregone Conclusion, now rebuilt with session musicians (Burrows, Wilkinson and the Clarke brothers) plus talented young rapper Dom (Smith) and tour manager Dan (Basden). He has secured seven dates in the Reading/Slough vicinity, although his PR machinery hasn't quite cranked into gear when they get on the tour bus and hit the road. But David doesn't let small, surly audiences or his aloof bandmates put him off.

Pretty much everything David says and does is utterly excruciating, both to the film's audience and to everyone around him on-screen. Even the lyrics to his songs are simply horrifying, preceded by rambling over-explained introductions during which the musicians grimace behind him. So it's hardly surprising that he finds himself with no friends, although the screenplay is careful to make it clear that a few key people like him anyway.

Gervais plays him unapologetically, never winking at the camera while taking the character deep into squirm-inducing inappropriateness. Much of this is very difficult to watch, so it's a good thing that the other characters undercut him at every turn. And that the film is punctuated by laugh-out-loud moments of unexpected comedy. Several costars register strongly, most notably Bennett as David's chucklehead work colleague. And Hartley is engaging as a woman with a soft spot for David's idiocy.

Gervais is playing with a resonant theme here, as David spends his life savings on a last-gasp attempt to achieve his lifelong dream before giving in to middle age. Ironically, there's also the sense that Gervais himself wants to be a rocker, and he invests plenty of talent into the catchy songs. In this sense, the movie is like a far less consistent riff on the classic mock-doc This Is Spinal Tap. Even so, it reminds audience that some dreams are too good to give up. And that sometimes it's probably better that they remain dreams while you carry on living your real life.

Nancy (Lively) is on a quest to find a secret beach her late mother once visited, and when her guide Carlos (Jaenada) takes her there, she feels like she's discovered paradise. After riding the waves with the locals and video-chatting with her dad and sister (Cullen and Legge), she decides to stay out to catch one last breaker. Then a few hundred metres from shore, she's attacked by a great white and takes refuge on a rock that's only above the surface at high tide. Injured and alone, she has to get creative to survive.

In the introductory section, the script has a nicely loose sense of realism, with witty banter between Nancy and Carlos and a careful attention to detail as she prepares to hit the surf. There are the usual bits of back-story, such as grief over her mother's death and her neglected medical school studies. This adds a hint of emotional depth as well as convenient explanation for her improvisational first aid skills.

Director Serra shoots with whooshing camera movement, prowling above and beneath the surface while creating a sharp sense of isolation on this postcard-ready beach. He also playfully hints at the underwater threat, nodding at Jaws while throwing in a friendly school of dolphins. Then the enormous shark pounces and things turn grisly and desperate. And the momentum is maintained with Serra's visual flourishes, including a luminous school of jellyfish that offers protection and pain. As the title says, these aren't deep waters, and Serra plays on that irony.

But of course, none of this would work without an intensely committed performance from Lively, who makes the audience feel each grimace of pain as we contemplate her every desperate escape idea. Much of her dialog is between an injured seagull trapped with her on the rock, plus some hopeful screaming at passersby. But watching her work out how to survive in this extreme situation is fascinating. It may be somewhat simple, but there's never a dull moment, and much of it is nail-bitingly suspenseful.