AS Denise Mina’s latest novel opens, we find ourselves in the company of two kidnappers. They’re not killers yet, but soon enough they will be. By the end of the breathless first chapter, a woman is dead and a man is consumed by the guilt over the manner in which her life has ended. Mina’s starkly compelling prose only serves to enhance the effectiveness of this set piece, making it impossible to resist the urge to find out what happens next.

Like the best of Mina’s work, Blood Salt Water probes beneath the public faces of community and family. In this case, Helensburgh provides the backdrop in which characters have reached the middle-class, gluten-free organic dream that is about to come crashing down about them.

Below the surface, dissatisfaction and resentment fester. Local chef Boyd Fraser loathes his own menus and his customers: “bringing organic eggs, blah blah blah. Supporting our local blah blah blah. He knew that the blah blah was their profit margin. Customers only paid five-fifty for their six eggs because of the blah blah.” But he continues to serve them, hiding not only his own resentment but also his boredom with everyday life, resulting in a build-up of pressure that will unravel his marriage and bring him into the centre of a conspiracy involving local racketeers, a money-laundering scam and a case of oddly stolen identity.

Iain Fraser, no apparent relation, is living with his own secrets. As one of the killers we met at the start of the book, he’s hiding his own guilt and shame, resulting in a series of physical symptoms and near hallucinations that bring him close to the edge of breakdown. He knows he’ll be caught, but he doesn’t know when or how.

Neither man expects to be in the crosshairs of Mina’s popular returning protagonist, DI Alex Morrow, last seen in The Red Road. Dealing with her own personal problems after arresting her half-brother, a known gangster, she’s now overly involved in an investigation designed to break a money-laundering scheme. The inquiry is proceeding apace until one of the suspects disappears, reported missing by her own children. As Morrow attempts to find the woman, she must dig past half-truths, lies and ulterior motives to discover a sinister truth that connects all these seemingly disparate threads. Her investigation will throw her in the path of crooks, fraudsters, adulterers, injury claims specialists and, of course, the big issue that no Scottish author, post-referendum, can afford to ignore.

Mina has never been one to shy away from politics, and Blood Salt Water uses the timing of its narrative to sketch a natural and surprisingly understated picture of the country as it was in September 2014. Surprisingly, given the strength of feeling many had, and still have, regarding the events of that time, Mina remains neutral in her portrait, showing both the passion and insanity of intense political debate. Morrow herself is exhausted, not only from her work but also from the constant inquiries as to which side she supports, describing her typical days as “liars and politics” and reminding fellow officers not to display political badges on duty. Mina’s fiction has always been subtle, and the small moments are often the most rewarding.

The “thrum” of the referendum is everywhere in this book, buzzing away in the background, providing a context for the main story. People try to make sense of the ceaseless coverage in the media and constant debate on the streets while continuing with their lives. Lesser writers would put the issue front and centre. Mina is too clever for that. She doesn’t offer answers or rhetoric; simply a sense of people aware that bigger things are happening around them.

Mina employs her procedural elements with a similarly light touch, making Morrow and her team part of an ensemble cast instead of the primary focus. Their efforts to uncover the truth behind the missing woman are only one element of Mina’s complex plot. The joy comes in seeing how these multiple strands eventually collide in ways that only seem inevitable in retrospect.

Most crime novels concern themselves with secrets and guilt, but it’s the rare author such as Mina who can make us forget we are reading about fictional creations, and whose astute understanding of psychology shifts the tension beautifully from wondering whether the culprits will be caught to speculating on how the lives of any of these characters could ever be the same again.