More gripping than The Hunger Games, The Vault by Emily McKay is the third in this series following on from The Farm and The Lair.
In a world where vampires rule and teenager humans are quarantined as a food source, there is only one choice: resist or die. But fighting the Ticks comes at a terrible cost to twin sisters Mel and Lily and their best friend Carter - with Lily exposed to the Tick virus and lying in a coma, it's up to Mel and Carter to search for the cure - but time isn't on their side.
With every passing heartbeat, Mel is becoming more and more purely vampire.
Now their only choice is to split up in a race to save Lily - and to save humanity.