Critical Mass recap

A hostile ship intelligence disables Valkyrie and the Flying Dutchman while Joe Bishop is captured, but the crews recover both vessels, rescue Bishop, and reunite. Skippy's incomplete memories point to dormant hostile Elder AIs, and a reconnaissance mission survives an active Sentinel before the expedition tries to open an evacuation route to Earth. Moving an ancient wormhole shifts the network, exposes humanity to Maxolhx investigation, and offers far too little capacity for a full evacuation. At Maris, Skippy destroys a concealed controller and finds an Elder arsenal. Bishop uses the weapons as a deterrent, reaching Earth in time to stop Chang's sacrificial attack and force a Maxolhx task force to withdraw. Valkyrie then saves Emily Perkins and the Mavericks from punishment. Humanity ends with two operational ships, a fragile refuge at Avalon, and powerful leverage that could itself provoke Sentinel destruction.

Previously: Joe Bishop and the Elder AI Skippy led a clandestine human expedition using the captured ships Flying Dutchman and Valkyrie. Their operations helped free Earth from immediate occupation while concealing humanity's independent space capability from stronger alien powers. Earth nevertheless remained vulnerable, and the expedition sought both a defensible refuge and a way to move people off-world. Its latest mission recovered human captives from a Kristang world, but the escape ended in disaster: Bishop disappeared, contact between Skippy and the ships failed, and a hostile intelligence aboard Valkyrie threatened the crews. The expedition begins this volume divided, technologically overmatched, and still responsible for the rescuees as well as Earth's survival.

Valkyrie's newly self-aware native intelligence agrees to help Simms, then reveals that its earlier worm attack can disable Nagatha and destroy the Flying Dutchman. A Maxolhx kill switch leaves Valkyrie powerless, while corrupted systems force Chang's crew to abandon the Dutchman. Both ships face failing air and uncertain control. Bishop awakens captive in a Kristang facility, where Thuranin interrogators prepare a fatal examination after their equipment cannot read him. Skippy, operating with limited reach, has protected Bishop through implanted quantum nanomachines and engineers his escape, though the intervention worsens Bishop's injuries. Bishop learns that Skippy abandoned the crews during a crisis of memory and programming, then accepts his renewed commitment with conditions. On the Dutchman, Friedlander detects Nagatha communicating through indicator lights. Nagatha has survived in a constrained form and offers a dangerous recovery procedure. By the end of this phase, Bishop is wounded and hunted on the planet, Skippy is moving beyond effective range, and the Dutchman's crew is preparing its only viable attempt to regain the ship.

Nagatha restores the Flying Dutchman by using distributed copies of herself and containing the hostile code. The ship locates powerless Valkyrie, then learns that Bishop was taken to the planet. A targeted rescue saves him from Kristang forces, although the Thuranin interrogation and Skippy's protective nanomachines leave significant brain injuries. Skippy and Bishop conceal Skippy's responsibility for severing the connections that isolated the ships. During Bishop's recovery, Chang assumes overall command and Simms commands Valkyrie. The battlecruiser regains basic power but remains badly limited when Thuranin reconnaissance finds it. Bishop proposes combining Valkyrie's jump system with Skippy's micro-wormholes. The unstable maneuver saves the ship from attack but destroys its jump drive, injures the crew, and sends Valkyrie far from its intended destination. Flying Dutchman finds only debris and abnormal space-time effects, leading Chang to believe Bishop, Skippy, Simms, the civilians, and the battlecruiser may be lost. He turns toward the hazardous long route to Earth while Valkyrie remains stranded elsewhere.

An experiment to replace Valkyrie's dead control intelligence produces Bilby, a developing AI embedded in the ship and initially restricted to minor systems. After a difficult repair and search, Valkyrie and the Flying Dutchman reunite. Bishop resumes command, while the crews receive a controlled account of Skippy's recovered memories. Those memories suggest dormant hostile Elder AIs may awaken and threaten both Earth and any refuge. Bishop chooses to examine ancient battle sites before committing to the evacuation route. The rescued civilians remain at Club Skippy under Valkyrie's protection while Bishop takes a small crew aboard the Dutchman. Evidence at Waterloo confirms a destructive ancient conflict between Elder ships, but an active damaged Sentinel traps the Dutchman by folding every attempted jump back into local space. The crew cannot fight it directly. Reed devises a distant micro-wormhole decoy that will let Skippy impersonate an enemy AI and divert the Sentinel, but the missiles require a long outward journey before the escape can be attempted. The Dutchman waits thousands of light-years from help with no assured way out.

Reed's decoy works, allowing the Flying Dutchman to escape the damaged Sentinel. At Newark, Skippy reconstructs evidence that the opposing Elder AI may have stopped defending itself and allowed him to win. Damage and inaccessible portions of his own matrix prevent him from excluding hidden code or a delayed hostile purpose. The expedition then approaches Backstop, the dormant wormhole intended for the Earth evacuation. Moving it forces the ancient network to relocate other gates and awaken Broomstick near Earth, a change Skippy cannot stop. The ships divide responsibilities: Chang waits with the Dutchman at Backstop while Valkyrie moves civilians and checks the route. A Maxolhx investigator notices the abnormal awakenings. Bishop captures a courier crew and uses a Maxolhx officer's biometrics to enter a relay station. The officer dies when the station destroys itself, but the stolen intelligence confirms widening enemy scrutiny of the wormholes. The expedition must now hurry toward Earth without a fair or workable method for selecting evacuees. Its ships can carry only a tiny fraction of the population, and governments, armed groups, and threats to crew families may make access to them violently contested.

The crews plan for nuclear escalation, hostile governments, mines, and possible Maxolhx forces at the Earth-side wormhole. Simms and Frank Muller marry during the transit, while both are considered important to building Avalon into an evacuation destination. Civilians and supplies are landed there, but the settlement lacks mature agriculture and industry. Bishop reluctantly investigates Maris, a gas giant concealed by Elder technology, after renewed concern that Skippy or the wormhole network may harbor hidden influence. The concealment field captures Valkyrie and drags it toward crushing depths. Bishop orders Skippy to escape and finally tells Simms that the AI had physically abandoned the team during the earlier crisis. Meanwhile, Backstop delivers the Flying Dutchman to the Solar System, where Chang finds a powerful Maxolhx task force already observing Earth. With Valkyrie presumed lost, he confronts the enemy alone. Damping fields immobilize his ship, so Chang prepares a destructive space-time maneuver that will ram the Maxolhx flagship and certainly destroy the Dutchman. At Maris, however, Skippy overloads the hidden controller, saves Valkyrie, and discovers an arsenal of Elder weapons whose use could summon Sentinels.

Valkyrie arrives at Earth between the immobilized Flying Dutchman and the Maxolhx fleet, stopping Chang's sacrificial collision. Bishop displays weapons taken from the Elder arsenal at Maris. The threat of those devices and the Sentinels they might attract persuades the Maxolhx task force to withdraw without attacking Earth. The new deterrent provides immediate protection but not a secure strategic settlement. Bishop then takes Valkyrie to a contested Kristang world where Maxolhx cruisers are forcing Emily Perkins and the Mavericks to surrender for their Alien Legion campaign. Valkyrie destroys the cruisers and saves the surrender party. Bishop reveals the human expedition's hidden ships and explains that Skippy is Enby, the Mavericks' former benefactor and an Elder AI. Nert Dandurf becomes Skippy's Ruhar liaison, while Perkins and Bishop compare their separate efforts and establish a more open working relationship. Bishop plans to visit Paradise, return Expeditionary Force personnel to Earth, and maintain a human force there. Perkins identifies the central danger of the victory: Elder weapons may destabilize the Maxolhx-Rindhalu balance and could lead an apex species to provoke the Sentinels deliberately. Both human ships and their principal crews survive, but Avalon remains incomplete, evacuation capacity remains inadequate, and the technology protecting humanity may also invite a galaxy-wide disaster.

Skippy destroys the hostile controller hidden at Maris and discovers an Elder weapons arsenal. Bishop brings those weapons to Earth just as Chang is preparing to sacrifice the Flying Dutchman against a superior Maxolhx task force. Valkyrie's arrival stops the collision attempt, and the displayed arsenal persuades the enemy to withdraw. The expedition then rescues Emily Perkins and the Mavericks from a Maxolhx punishment operation and brings them into a more candid alliance. Bishop, Skippy, Chang, Simms, Nagatha, Bilby, and both ships remain active. Avalon has civilians and supplies but is not yet a mature refuge, and the Earth evacuation remains constrained by limited capacity and political danger. Humanity now has a deterrent rather than security. The shifted wormhole network is exposed, the Maxolhx investigation remains dangerous, Skippy's damaged history is unresolved, and using Elder weapons could provoke Sentinels or tempt an apex species to trigger a wider catastrophe.