Sasha and Connelly have faced off against murderers, terrorists, corrupt officials, and international crime rings ... you name a bad guy, and they've probably taken him (or her) down. In Insidious Threats, they team up against their most powerful adversary yet. But has the wife-and-husband duo finally met their match?

When Landon Lewis plunged to his death from his office window, he left behind a slew of unanswered questions. The one that weighs most heavily on Leo Connelly's mind is what, exactly, is he supposed to do with the package Landon sent him the day he died?

As a special agent for a secretive government agency, Leo has the connections and resources to crack open the encrypted flash drive, but the letter accompanying the drive gives him pause. The dead man's words are so cryptic, so ominous, so chilling, that Leo decides this is an operation best conducted off the books, far away from his agency's watchful eye—and his wife's.

Under ordinary circumstances, Sasha McCandless-Connelly would notice when her husband is hiding something. Unfortunately, she's distracted by the behavior of her former law firm. When Prescott & Talbot's managing partner resigns abruptly, then disappears, the firm leaders come to Sasha—ostensibly for help. But she knows better than to trust them.

As Sasha digs into the truth behind Cinco Prescott's disappearance, Leo unravels the mystery of Landon's flash drive. What they uncover separately leads to one inescapable conclusion: they'll have to work together to dismantle the dangerous, dystopian Mjölnir network without being detected ... or die trying.