The Keeper of Lost Causes / Mercy, the first installment of Jussi Adler-Olsen’s international bestselling Department Q series, features the deeply flawed chief detective Carl Mørck, who used to be a good homicide detective – one of Copenhagen’s best. Then a bullet almost took his life. Two of his colleagues weren’t so lucky, and Carl, who didn’t draw his weapon, blames himself.

So a promotion is the last thing Carl expects.

But it all becomes clear when he sees his new office in the basement. Carl’s been selected to run Department Q, a new special investigation division that turns out to be a department of one. With a stack of Copenhagen’s coldest cases to keep him company, Carl has been put out to pasture. So he’s as surprised as anyone when a case actually captures his interest. A politician vanished without a trace five years earlier. The world assumes she’s dead. His colleagues snicker about the time he’s wasting. But Carl may have the last laugh, and redeem himself in the process.

Because she isn’t dead … yet.

How was it?

Jussi Adler-Olsen’s The Keeper of Lost Causes (Mercy in the UK) introduces us to Carl Mørck, a deeply flawed detective navigating guilt, trauma, and a new position in Department Q—a unit relegated to solving cold cases. Set against the atmospheric backdrop of Copenhagen, this first entry in the Department Q series is a slow-burning mystery that mixes dark humor, grounded suspense, and layered character development.

From the very first page, the tone is dark. Carl Mørck, reeling from a traumatic shooting that left one colleague dead and another paralyzed, is “promoted” to Department Q—a move meant more to sideline him than to reward his skills. He’s literally relegated to a bleak basement office where he’s eventually joined by Assad, his enigmatic and weirdly capable new assistant. While I didn’t like Assad’s introduction in the novel because it leans on clichés, his dynamic with Carl evolves into one of the book’s strengths, blending levity with intrigue.

The novel alternates between two timelines: the present investigation of a missing politician, Merete Lynggaard, and the chilling events leading to her disappearance five years prior. These two narratives build tension slowly but steadily, contrasting Carl’s gritty investigation with Merete’s harrowing ordeal. Although the writing style is plain, it’s effective in capturing the story’s bleakness while maintaining just enough optimism to keep me engaged.

The humor is subtle but adds a surprising layer to the grim narrative. Carl’s sardonic internal monologues and interactions with his colleagues provide moments of levity that balance the darker themes. Lines like, “Carl sent a message from his brain to his hands that it was still illegal to strangle people,” is a welcome dose of dry wit to the story.

While The Keeper of Lost Causes didn’t immediately dazzle me, it excels in creating an atmosphere of suspense and dread. The payoff is grounded, offering a resolution that is not overly neat. This realism, coupled with the book’s bleak yet hopeful tone, sets it apart from more formulaic crime thrillers.

Ultimately, my prior experience with the film adaptation likely influenced my appreciation for the book, but Adler-Olsen’s ability to craft a propulsive, character-driven mystery ensures I’ll continue the book series.

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