Blue Labyrinth is a novel by Douglas Preston and Lincoln Child first published in 2014. It is part of their informal Agent Pendergast series, and the fourteenth book overall.
When Pendergast discovers the lifeless body of one of his enemies on the front doorstep of his mansion, he begins a thorough investigation to discover the killer. A rare turquoise stone in the victim's stomach leads him to a deserted Californian mine, but awaiting him there is a fiendish trap laid by a mastermind who wants revenge against the entire Pendergast family.
This novel provides examples of:
- Ascended Extra: Sergeant Slade turns out to be a minor character from Relic - the FBI agent who takes over from Coffey near the end of the book. He's basically The Dragon here.
- Asshole Victim: Dr. Frisby acts like an absolutely prick to Margo whenever he shows up, making it hard to shed any tears when Slade disposes of him.
- Awesomeness by Analysis: Barbeaux learns of Alban's abilities through careful observation, and devises a non-plan to deal with them.
- Big Damn Heroes: When Constance is captured by Barbeaux's men while attempting to get the ingredients needed to cure him, Pendergast appears after realizing what she's doing and manages to take out a few henchman. His condition overtakes him and he nearly dies afterwards, but his actions provide enough of a distraction for Constance to escape.
- The Bus Came Back: Margo Green returns after nearly a decade since her previous appearance and has to face her fear with the museum again after her near-fatal encounters with both Mbwun and Diogenes.
- The Cavalry Arrives Late: Happens with D'Agosta twice. He doesn't appear to with reinforcements to aid Margo until long after Slade has been killed, and they don't arrive where Constance is until after she's taken out all of Barbeaux's hitmen and Barbeaux himself.
- Continuity Nod:
- The nameless secret agent from Brimstone returns, offering to help Pendergast find out what happened to his son.
- The police officer Slade is a minor character from Relic, as noted above. Late in the novel, he explains that he was kicked out of the FBI after Relic's events which is why he became a Dirty Cop.
- Dead Person Conversation: During one chapter Pendergast dreams of meeting Diogenes. At the end, it's implied he had a similar meeting with Alban.
- Demoted to Extra: Laura Hayward makes only a brief, nonspeaking cameo.
- Dirty Cop: Slade turns out to be on Barbeaux's payroll.
- Don't You Dare Pity Me!: After learning that Pendergast has been given a concentrated dose of his ancestor's elixir Constance urges Pendergast to seek medical attention, which makes him respond by snapping at her. He later apologizes to her about his actions.
- Have You Told Anyone Else?: Barbeaux asks this about Angler when the cop discovers some dirty findings in his company. When Angler replies no, his partner Sgt. Slade proceeds to shoot him in the head, revealing himself as one of Barbeaux's stooges.
- Indy Ploy: Barbeaux explained that his plan to kill Alban was not to have a plan; it had to be something without malice or forethought. Alban was killed when Barbeaux spontaneously strangled him with a shoelace.
- Inspector Javert: The police officer Peter Angler begins thinking Pendergast is responsible for Alban's death. His investigation eventually leads him to the Big Bad, thought Angler is unaware of this. Angler then gets shot by his partner, who was working for the Big Bad all along.
- Karma Houdini Warranty: Karma catches up to Alban big time since he was last seen: not only was his wife killed in an unrelated attack, but his attempt to stop Barbeaux from seeking revenge against his father backfires horribly and results in his death.
- Laser-Guided Karma: In the climax, it's revealed that Barbeaux is suffering from his son's illness - the same one he gave to Pendergast.
- Must Make Amends: Alban is revealed to have done this, begging his brother for forgiveness and attempting to call off Barbeaux's plot. In the epilogue, Pendergast decides he must make amends for his great-great-grandfather's tainted medicine and sells most of his family's property. He uses the proceeds to create a charity.
- Outliving One's Offspring: The motivation behind Barbeaux's actions.
- Race Against the Clock: Constance, Margo, and D'Agosta have to struggle to find a cure when Pendergast is poisoned by Hezekiah's elixir.
- Sins of Our Fathers: John Barbeaux targets Pendergast for the actions of his great-great grandfather Hezekiah, whose elixir poisoned those who took it, as well as causing a birth defect in some of the descendants of its victims. Barebeaux's son was one of them, which led him to die at a young age. Barbeaux promises to even target Tristram for the same reason.
- The Worf Effect: Alban's death. Both Pendergast and the reader recognize that whoever killed him must be especially nasty, since Alban had precognitive abilities.
- Your Days Are Numbered: Barbeaux poisons Pendergast with a concentrated form of his ancestor Hezekiah's elixir. While it normally took several doses before it would become lethal, the stronger dose means Pendergast will be dead within days.