A trio of Irish cousins grew up together, holidaying in their family’s house, now owned by their bachelor uncle, Hugo. Toby, the narrator of The Wych Elm, works in publicity and marketing for an art gallery; Susanna is a wife and mother with a sideline in drawing up spurious family trees; Leon is a gay expatriate with a derisive tone and an unhappy personal life who works for ‘an achingly hip indie record label’. They are brought together again when Hugo becomes terminally ill and Toby is attacked in his own flat and left with brain damage. It makes sense for Toby to convalesce at the Ivy House and, at the same time, keep Hugo company during his last few months. Toby’s perfect girlfriend, Melissa, joins them and goes out of her way to keep Hugo happy. One short phrase sums up the life they have there together: ‘mutual, grave, tender’.

Everything changes when a skeleton is discovered inside a hollow tree in the garden. The rest of the novel moves between the police investigation and the slow discoveries Toby makes about himself, his cousins and their friends. The novel is prefaced with Ophelia’s ‘Lord, we know what we are, but know not what we may be’ and includes many references to the self and self-knowledge, but for me the most interesting aspect is the exploration of guilt and responsibility. All crimes have long ancestries. Tana French’s account of this one is engaging, convincing and, above all, terribly sad.

Don Winslow has now finished his Mexican cartel trilogy with the enormous (in every sense) The Border. Completing the series that began with The Power of the Dog, he drags Art Keller out of retirement in Mexico to take over as head of the DEA in Washington, DC. The war on drugs has lasted for decades, costing more lives than America’s wars in Afghanistan and the Middle East, as well as billions of dollars, but the problems caused by drug-taking have got worse and worse. Keller, a Vietnam veteran and a CIA employee, has worked undercover for years. He has witnessed unspeakable cruelty, seen friends and enemies killed in huge numbers, and has himself broken the law in his fight to destroy the worst of the drug kings.

While the Mexican cartels battle for supremacy south of the border, Keller tracks the money they are attempting to launder into the heart of the American establishment. Winslow’s knowledge of all aspects of the drug trade is immense and he shows not only the grand scale of the disaster it has set in motion but also the small individual tragedies it creates. His novel follows two children who flee the horrors of life on a Guatemala City rubbish tip, a pair of heroin addicts in Washington and a whole series of variously corrupt and criminal dupes of the cartels’ masterminds. The few examples of human decency and affection flicker like minute candle flames amid the darkness of the drug trade. Winslow’s trilogy is a monumental and magnificent achievement. The Border provides all the heart-banging excitement of the best kind of thriller.

Theo is a psychotherapist at The Grove, a rundown mental hospital that is threatened with closure. His chief interest is Alicia Berenson, convicted of killing her husband and now mute. Having attacked a fellow patient, she is heavily sedated and it seems unlikely that even the empathetic Theo will be able to make her talk. His first-person narrative is interspersed with sections of the secret diary she kept before the murder, which make it clear that her case is far from straightforward. Theo himself is an interesting character. His childhood was made terrible by his erratic and violent father. Like many who work in the psychiatric professions, he is trying to heal himself by healing others, but Alicia represents an enormous challenge. Packed with references to and quotations from the works of such giants as D W Winnicott and John Bowlby, this novel is as twisty and devious as anyone’s subconscious.

Never has the adage ‘what doesn’t kill you makes you stronger’ seemed as relevant as it does in the context of The Lost Man, Jane Harper’s third novel. With the only teaching for children coming across the radio, regular droughts and a punishing sun that causes many inhabitants to develop skin cancer, the Australian outback teaches resilience when it doesn’t send its residents mad. Three brothers generate the action in The Lost Man: Cameron, who has died of thirst and exposure; Nathan, who has been summoned from his failing farm by the rest of the family to deal with the fallout; and Bub, the youngest, who has stayed in the family home with their mother and Cameron’s wife and daughters.

Nathan is the nearest thing to a detective in the novel, but Harper is much too sophisticated a writer to set up clues and red herrings and have him chasing the truth in the traditional way. Instead, she shows with great skill how he deals with his own failures and hellish loneliness, while at the same time coming to understand what has been going on with the rest of the family in the house where he grew up. Harper’s first novel, The Dry, won many awards, but this one is even better. Her depiction of the extraordinary landscape is superb, as is her account of the psychological and emotional burdens it imposes on the people who try to make a living within it.

Elly Griffiths, whose most recent novel was the ambitious The Stranger Diaries, now returns to her popular series featuring Dr Ruth Galloway. Set in East Anglia and dealing with Ruth’s twin careers as an academic and a forensic archaeologist, the series could best be described as ‘modern cosy’. It takes its tone from Ruth, who is intelligent, enquiring, loyal, funny and kind.

She is the single mother of seven-year-old Kate, and still has feelings for Kate’s father, the married DCI Harry Nelson, which she keeps under control by actively dwelling on how much he can irritate her. Nelson doesn’t keep his feelings under control, fantasising about getting Ruth’s male friends convicted of something or having them deported. In this adventure, the two deal with the belated discovery of the body of a child who went missing decades ago. The familiar cast of characters are on excellent form, including the druid Cathbad, who has stopped wearing his cloak because his young son has a very low embarrassment threshold. For comfort and entertainment, this series is ideal.

Following on from C J Tudor’s successful debut, The Chalk Man, comes a novel about bullying, cruelty and deceit in an area of north Nottinghamshire still reeling from the collapse of the mining industry. Joe Thorne, the narrator, who grew up there but escaped, has now returned to teach at the school he attended in his youth. He has a limp, a gambling habit, serious debts and a great many secrets. Battling with the problems of a failing and poorly disciplined school, Joe also tries to find out exactly what happened to a dead woman and her son, slowly revealing his own desperate past in the process. Tudor keeps the novel moving at a fast pace, but the human depravity on display is extreme and there is no redemption to soften the brutality.

Alan Judd’s Charles Thoroughgood is the current head of MI6 but yearns for an earlier time, when political correctness was unknown and civilised professionals ate a good lunch with wine every day. He is considering retirement. Unfortunately one of his most trusted subordinates raises questions about the man most likely to succeed him, who is informally running an agent within the EU’s Brexit negotiating team. For all kinds of political reasons this operation has to be sub rosa, and Charles is suspicious. At the same time his professional and personal lives are complicated by his wife’s godson, who has married a Muslim and converted to Islam. Her family are delightful and observant without being fanatical, but he has some highly dubious friends, who are alarming Charles’s colleagues. This book, like Judd’s other spy novels, has all the virtues of a well-researched plot, intelligent prose and topicality.

An investigative reporter hunting for evidence against a commodities conglomerate, Casey Benedict is in an expensive bar dressed to the nines when she overhears someone apparently talking about an organisation that provides the ultimate big-game shoot – with human beings as prey – for the rich, powerful and discreet. She and her bosses know at once that chasing this story could be dangerous, but they can’t resist. The account of their own big-game hunt is eye-popping in its revelations of undercover journalists’ tactics. In the early part of the novel the writing is self-consciously colourful, but once the investigation moves towards the world’s refugee camps the tone settles and Holly Watt’s knowledge and experience as an investigative reporter add a seriousness to this fast-moving, if not altogether convincing, thriller.