When a sinkhole opens up and swallows one of Bayport's historic statues, Frank and Joe suspect something--or someone--shady at play. They jump at the chance to investigate ; Joe as a member of an urban exploration club, and Frank as photographer for the school paper. But in the thick of their search, the boys stumble upon an entire underground city that's been abandoned for years. Now the city is home to a cultish band of criminals who plan to take...

"Charlotte - aka Charlie - a pretty redhead, sets up an expedition to find her brother. The young scientist, who disappeared underground several months ago, claimed - to everyone's astonishment - to be able to prove the existence of Hell by using Darwin's theory of evolution! The little group, led by Charlie, plunge underground in his pursuit. The deeper they progress into the entrails of our planet, the more they enter another world that hides other...

"Stel Caine rises from the depths to the sun-blasted surface of the Earth, the first human in millennia to do so. She's closer than ever to discovering the deep-space probe, which holds within it the potential to save all mankind. But eons of radiation have given birth to strange new life, and humans are no longer the dominant species here. Meanwhile, deep below the waves, Stel's daughters start their own journeys topside. Will this family reunion...

Four generations ago, the Earth was rendered uninhabitable and those who remained were forced underground. In Compound Eleven, the hierarachy of floors is everything and on Eve Hamilton's floor, they fight. When she meets a boy from the top floor, Eve is no longer content to just survive, she is ready to fight for freedom.

As Will Burrows continues to search for his lost archaeologist father in the strange underground world he has discovered, he stumbles across a sinister plot with terrible implications for the world above.

In the year 241, twelve-year-old Lina trades jobs on Assignment Day to be a Messenger to run to new places in her decaying but beloved city, perhaps even to glimpse Unknown Regions.

"The final arc of Low. Salus rises. The Burnt Legion attacks. Stel Caine faces the greatest challenge to her hope yet: the rage of her daughter, the Helmswoman, Della."--Provided by publisher.