Fakery is promised in the opening image of The Mercy. A smiling beauty water-skis over sunny seas, only for the camera to pull away and reveal she is part of a maritime expo in a vast exhibition hall. One of the other exhibitors is an inventor called Donald Crowhurst (Colin Firth), who enlists his beaming sons to demonstrate his Navicator, a simple tool to guide sailors on the high seas. Optimism is laced with a tincture of despair.

Take one off-the-wall spoof spy thriller that becomes an unexpected hit. Add a bunch of gratuitous guest stars (mostly American). Stretch formula to 140 minutes. Stand clear and wait for the box office stampede.

If you happened to catch the second part of the Bridget Jones story – Bridget Jones: The Edge of Reason (2004, directed by Beeban Kidron) - on terrestrial television recently, or have read the character's creator Helen Fielding's novel Mad About the Boy, you may be confused by the opening sequence of the third instalment in the film franchise, Bridget Jones's Baby. It begins with Bridget, single and childless at 43, sitting alone in her flat on her birthday, with a glass of wine and a cake with a single candle, singing along to “All By Myself”.

Irish director Pat O’Connor’s 1987 adaptation of J L Carr’s A Month in the Country has been unavailable for many years; this BFI reissue was only possible after a few surviving prints were located. It’s a disquieting watch – a superficially English reflection on faith, loss and recovery, full of dark shadows and sharp edges. Simon Gray’s screenplay wisely avoids using a voiceover, the plot’s subtleties conveyed instead by a well-chosen cast.

Imitation is the sincerest form of flattery, the saying goes – and Kingsman: The Secret Service is a cracking part-homage, part-pastiche of the James Bond franchise (and other British spy movies) done with knowing comedy, élan and obvious affection. It's based on The Secret Service comic book created by Dave Gibbons and Mark Millar, and is directed by Matthew Vaughn (Kick-Ass, X-Men First Class), and here he reunites with Jane Goldman, who also provided scripts for his previous works.

An ageing misanthrope is given a new lease of life and a fresh outlook by a pretty, young woman. Woody Allen wheels out this tired old trope for his 44th feature film set in his favourite era on the French Riviera with a light romantic yarn between Colin Firth and Emma Stone playing out as predictably as one might imagine. Thankfully this old fashioned unravelling mystery proves to be a far more enticing affair than anticipated due to the striking backdrop of glitzy 1920s fashion, sparkling evening soirees and expertly curated jazz accompaniment.

Everyone loves a homegrown hero – and they don’t get more homegrown than Before I Go to Sleep, the thriller written and directed by Rowan Joffe, son of Roland Joffe, director of The Killing Fields and The Mission. Before I Go To Sleep is, arguably, one of the most anticipated British films of 2014. The script is based on the Faber Academy sensation of 2011, ex-audiologist S.J. Watson’s novel of the same name.

Two knotted horrors stained West Memphis, Arkansas in 1993. Three 8-year-old boys, Stevie Branch, Christopher Byers and Michael Moore, went cycling on a sunny spring afternoon. Their torn, bruised and in Byers’ case castrated bodies were dragged from a stream the next day. Three local teenage boys, black-garbed outsiders Damien Echols, Jason Baldwin and Jessie Misskelley, Jr., were then tried for the crimes with a carelessness, incompetence and prejudice which seemed actively malicious. This “West Memphis Three” sacrificed 18 years in jail, as authorities who had in some cases risen to power on the back of the verdicts ensured they stood, despite an overwhelming weight of evidence against them. A rare and nonsensical Alford plea allowed the three’s release, unpardoned but maintaining their innocence, in 2011.

The Peter Jackson-produced West of Memphis (2012) has the highest UK profile of several documentaries which made the case a cause celebre. It was a campaigning film, highlighting how little innocence can count in US justice’s venal byways. This first dramatic account treads a quieter, more circumspect path. Director Atom Egoyan is fascinated with buried, often traumatic secrets. A hunt for a missing, murdered child is the horror behind the sexual sadness and pain of Exotica (1994), and the yellow school bus glimpsed early in Devil’s Knot recalls the town who lose a bus full of children beneath the ice in The Sweet Hereafter (1997). There was a fairy tale elegance and heartbreaking profundity to the latter film. Egoyan’s response to West Memphis’s loss is intentionally less certain and satisfying.

Reese Witherspoon is Pam Hobbs, mother of murdered Stevie, and Colin Firth is private investigator Ron Lax, pictured above right, who helped destroy the case against the West Memphis Three. Both give diligent, unstarry turns. Witherspoon’s Hobbs is a Southern Christian who tears locks of her hair out in grief, but comes to doubt the Satanic conspiracy the accused are believed to be part of in a conservative town bent on retribution. Firth slips under the skin of the quietly decent and angry Lax, a prosperous private eye helpless to directly effect West Memphis’s kangaroo court. They blend in with a strong cast including Alessandro Nivola as Terry Hobbs, pictured above left with Witherspoon, Pam’s watchful, faintly dangerous husband, and Egoyan regular Bruce Greenwood as Judge David Burnett, almost drumming his fingers with impatience to get to the guilty verdict.

The grisly comedy of the flagrantly biased courtroom makes the injustice clear. Egoyan, though, also humanises the staggeringly inept police by showing them wading through the stream, discovering and holding the boys’ corpses: the spark for a 21^st century trial compared here to Arthur Miller’s Salem.

Egoyan wants to leave us off-balance, turned around by contrasting perspectives, engaged by the mystery of the murdered boys’ fate, not the documentarians’ solution to the accused boys’ innocence. He isn’t helped by a script where characters explain themselves in Hollywood-style speeches, even as Hollywood’s satisfying resolutions are spurned. It’s a film I want to see again, in case the deeper mystery Egoyan aimed for is lurking in its murderous woods and human masks. But it feels as if he’s missed his subtle mark, veering between convention and understatement to underwhelming effect.

Overleaf: Watch the trailer for Devil's Knot