A darkling plain (Mortal Engines #4)

The once-great traction city of London is now just a radioactive wreck, a ruin haunted by electrical discharges and the dashed hopes of the people who once called it home--people like Ton Natsworthy. Twenty years after he fled, intending to never return, he discovers that something stirs in the remains of the old city.

Tom and his daughter, Wren, aren't the only people interested. The desperate armies of the Tractions Cities and the Green Storm are also closing in, certain that whatever is saking shape holds the key to victory in their never-ending war. But it may be too late. Even as Tom and Wren hurry to uncover the mystery, Hester Shaw--estranged from her husband and daughter--tracks the resurrected Stalker Fang, who has found another way to end the war and all life on the planet. Fourth in the Hungry City Chronicles.