Books in the London Deep series are set in the future. The 'climate upgrade' failed. London is flooded. Rival police forces for kids and adults compete to keep the peace. Threadneedle is the third book in the series - although they can be read in any order. Serial rule breaker Jem and YPD officer Nick return to London to find that the city faces a new threat: a disease called Threadneedle. Adults are the carriers.