Like its ambitious companion novel Replica this far-reaching novel by the powerhouse author of Before I Fall & the Delirium trilogy digs deep into questions of how to be a human being in a world where humanity cannot be taken for granted In the world outside of the Haven Institute Lyra & Caelum are finding it hard to be human-and Lyra infected at Haven with a terrible disease finds her symptoms are growing worse When Caelum leaves without warning Lyra follows him seeking a pioneering organization in Philadelphia that might have a cure But what they uncover there is a shocking connection to their past even as their future seems in danger of collapsing Though Gemma just wants to go back to her normal life after Haven she soon learns that her powerful father has other plans for the replicas-unless she & her boyfriend Pete can stop him But they soon learn that they aren't safe either The Haven Institute wasn't destroyed after all & now Gemma is the one behind the walls Bestselling author Lauren Oliver brings the Replica duology to a shocking close in Ringer but like both Gemma & Lyra you won't be able to leave the world of Haven behind after you've turned the last page