A Darkling Plain is the fourth and final novel in the Mortal Engines Quartet series, written by British author Philip Reeve.
The novel won the 2006 Guardian Children's Fiction Prize and the 2007 Los Angeles Times Book Prize for Young Adult Fiction.
Setting The book is set six months after Infernal Devices. Wren Natsworthy and her father Tom Natsworthy have taken to the skies in their airship, the Jenny Haniver. After the apparent death of the Stalker Fang at the end of Infernal Devices, General Naga has seized command of the Green Storm and has signed a peace treaty between the Green Storm and the Traktionstadtsgesellschaft, ushering in a new era of peace and trade. Whilst Wren is enjoying life as an aviator, Tom misses Hester, and has been informed by a doctor that his weak heart means he only has a few years left to live. The Lost Boy, Fishcake, is secretly repairing the Stalker Fang, coming to regard her as the mother he never had. Theo Ngoni has returned to Zagwa and rejoined his family.
Explanation of the novel's title The title is derived from Matthew Arnold's poem Dover Beach. This excerpt of the poem appears at the beginning of the book:
This relates to the novel in several ways. The characters are indeed swept about, often against their will, by the "ignorant armies" of the Green Storm and Traktionstadtsgesellschaft, on the "darkling plain" of the Great Hunting Ground.
Reeve references his choice of title himself towards the end of the book when the character Nimrod Pennyroyal writes a book within a book titled Ignorant Armies.
The similarly titled, "As on a Darkling Plain", by Ben Bova in 1972 also takes its title from this poem.
Plot
Part One Six months after the events of Infernal Devices, General Naga, now leading the Green Storm following the presumed death of Stalker Fang, has brokered a truce with the Traktionstadtsgesellschaft, ushering in a new era of trade and peace.
Theo Ngoni returns to his hometown of Zagwa to reconnect with his family but thwarts an assassination attempt on Oenone Zero, wife of General Naga, now known as Lady Naga. In town to broker peace between Zagwa and the Green Storm, Zero suspects the attack was orchestrated by Stalker Fang loyalists. To prevent further danger, she arranges transport on a disguised merchant airship to rejoin Naga via an alternate route. Grateful for Theo’s assistance, she invites him along, and he accepts, hoping to find Wren during the journey. During the voyage, Zero’s servant Rohini is revealed as Cynthia Twite, a Green Storm spy who survived, and she attempts to kill Zero. Theo intervenes, but Cynthia escapes, causing the airship to crash. Both survive, but Zero is captured by air trader Napster Varley, who intends to sell her to the Traktionstadtsgesellschaft. Meanwhile, Theo is rescued from slavers by Hester Shaw and the Stalker Shrike, though Shrike’s abilities have been diminished by Zero’s earlier actions. Upon learning of Zero’s capture, Hester and Shrike set out to rescue her, knowing she can remove the "barrier limiting Shrike. When Cynthia reaches Naga’s base in Tienjing, she claims Zero was killed by the Zagwans, but Naga refuses to retaliate against the Tractionists. Cynthia then insinuates herself into a position within Naga’s household.
In the Traction City of Peripatetiapolis, Tom Natsworthy discovers that the bullet that Nimrod Pennyroyal shot him with in Predator's Gold has damaged his heart and he has not long to live, hiding this from his daughter Wren. Tom soon comes across a woman who looks strikingly like Clytie Potts, a London apprentice historian he once knew. When questioned, she tells him that her name is Cruwys Morchard and that she is transporting Old-Tech devices. Unconvinced, Tom and Wren decide to pursue her, travelling on the Jenny Haniver to Murnau, a Traktionstadtsgesellschaft city, where they meet Wolf von Kobold, the son of the Mayor of Murnau and commander of the traction city Harrowbarrow. Wolf believes that the survivors of MEDUSA may still be inside London, and the three agree to make an expedition to London.
Tom and Wren meet Wolf aboard Harrowbarrow, a burrowing Traction City that carries them closer to London. With Wolf in tow, they pilot the Jenny Haniver over the Green Storm border and reach London’s debris field. There, they find MEDUSA survivors who have rebuilt life in the city, now led by Tom’s former boss, Mayor Chudleigh Pomeroy. Garamond, the overly suspicious head of security, convinces Pomeroy to keep them around, worried they might spill the secret about London’s survival. Eventually, Tom, Wren, and Wolf come across a new traction town being built near the ruins, a project that began long before Magnus Crome unleashed MEDUSA. Seeing that “New London” has no wheels, Dr Childermass, the lead engineer, explains it uses Magnetic Levitation to float above the ground, reducing environmental harm. Wolf quietly slips away and returns to Harrowbarrow, plotting to consume New London and claim the technology for his own city.
Elsewhere, former Lost Boy Fishcake has partially rebuilt the Stalker Fang in Cairo. where its personality shifts between the compassionate Anna side and the ruthless Stalker side. Fishcake informs Fang that Cairo is stopping to trade with Lost Boy-controlled Brighton, where they steal a limpet before heading off to Shan Guo, where the Stalker plans to do something “important.” As they travel on foot, Fishcake and Fang reach a remote hermitage where Sathya, a former Green Storm commander and Anna’s old friend, lives in exile. The Anna side of the Stalker refuses to harm Sathya and seeks out Dr Popjoy, the London engineer who brought her back in Predator’s Gold, to remove the Stalker side. Against objections, Fishcake goes with her to Batmunkh Gompa. Before they can find Popjoy, the Stalker side reemerges and orders him to erase the Anna side. Popjoy explains that the brain he implanted in Rogue’s Roost came from an ancient “Remembering Machine” he discovered in the Arctic, meant to preserve nomadic culture. When he learns that Stalker Fang plans to reactivate ODIN (Orbital Defence Initiative), an orbital weapon equally destructive as MEDUSA, he protests—only for her to kill him. Stalker Fang then takes Fishcake with her to Erdene Tezh, her old home.
Part Two Napster Varley arrives in Airhaven, which is floating above the Traktionstadtgesellschaft, and unsuccessfully attempts to sell Zero to Wolf's father Kriegsmarschall von Kobold. Hester, Theo and Shrike arrive at the floating city and attempt to buy her from Varley, who asks for an extortionate price which they cannot pay. Hester and Theo discover Pennyroyal hiding in Airhaven in disgrace and debt after a newspaper exposed him as a fraud. Hester takes what remains of his money and heads to Varley's ship to buy Zero, with Theo accidentally mentioning to Pennyroyal about Zero being alive. With this knowledge and seeking to reclaim fame, Pennyroyal rounds up men from Manchester and marches to Varley's ship. Discovering a photograph of Zero that Varley placed on him, von Kobold attempts to rescue her to make further peace with Naga.
Hester's attempt to cheat Varley is discovered and he attacks her, but his abused wife kills him. As Hester and Zero make their way back, von Kobold finds them and helps them. Pennyroyal arrives with the Manchester men and a fight ensues where von Kobold is shot, but survives via his Old-Tech armour. Shrike manages to scare them away and gets Hester and Zero to their airship the Shadow Aspect and escape. Pennyroyal gets into an altercation with a journalist and falls from Airhaven and is assumed dead, but lands in the rigging of the Shadow Aspect. Stalker-birds arrive but escort the airship to a Green Storm air base where they are hailed as heroes. The base is soon attacked by the Traktionstadtsgesellschaft and Harrowbarrow. All escape in an airship heading east except Theo who stays behind to retrieve a letter that Wren sent him, but is seemingly killed by a bomb shell.
Wolf returns to Harrowbarrow and meets with von Kobold and the Mayor of Manchester Adlai Browne. With support from other Traktionstadtsgesellschaft cities, Browne intends to destroy the Green Storm, despite von Kobold wanting peace. In Tienjing, Naga is informed of the Green Storm air base being attacked but does nothing, disheartened by Zero's supposed death. Cynthia has been poisoning his green tea to make him helpless further and fanatically believes that the Stalker Fang will return.
Fishcake and the Stalker Fang, whose personalities seem to be merged, steal Popjoy's air yacht and reach Erdene Tezh and her old home. Inside, she starts to create a device which will relay orders to ODIN.
Part Three Theo survives the attack on the airfield and treks east across the plains toward London, where Wren's letter told him she would be; whilst the surviving Green Storm soldiers are transported off to Forward Command, an old traction city where Hester, Shrike and Zero were taken. Theo eventually reaches New London and is reunited with Wren, as well as warning the residents that the war between the Green Storm and the Traktionstadtsgesellschaft has restarted.
ODIN is fired upon Manchester and other cities by the Stalker Fang, killing Browne. Orla Twombley, a pilot formerly from Brighton, observes the destruction and reports to von Kobold in Murnau, telling him and the remaining cities to retreat from a Green Storm weapon. Naga receives communication that Zero is alive, and, realising that Twite has deceived him confronts her. Twite attempts to kill him, but ODIN fires on Tienjing. Naga survives but Twite is killed instantly in the blast.
The residents of New London see the firepower of ODIN from afar, and fearing that it is a Green Storm weapon, make plans to head north when the city is finished. Tom, fearing for Wren, takes the Jenny Haniver to Tienjing, hoping to convince Naga to not use his supposed weapon. Tom leaves a letter to Wren saying his goodbyes and entrusting Theo to take care for her, admitting that he is dying. Wolf hears of Manchester's destruction and is determined to continue on to London, claiming to his underlings that Harrowbarrow's creeping nature will help them survive.
Part Four Hester, Shrike, Zero, and Pennyroyal head to Batmunkh Gompa to reunite with Naga, who’s been evacuated there. They learn that both the traction cities and Tienjing have been destroyed, which Shrike figures must be the work of Stalker Fang. Zero plans to speak with Popjoy, the creator of Stalker Fang, hoping he knows how to stop her for good. Meanwhile, Wren finds Tom’s letter and sets out with Theo to follow him, but they’re stopped by Garamond, who suspects them of being Green Storm agents plotting to betray New London. It turns out Pomeroy died in his sleep after Tom left, and Garamond has taken over his role. He arrests Wren and Theo, but Childermass frees them, urging them to flee to a Green Storm settlement. It’s then revealed that Childermass is Bevis Pod’s mother.