Each Night Was Illuminated, by Jodi Lynn Anderson

When Cassie and Elias were young children, they witnessed a horrific train accident together. Cassie lost her faith in God that day, unable to conceive how such horrible suffering could have occurred.  And shortly after that, Elias moved away.  In the ensuing years, they corresponded and stayed in touch.  Elias returns when they are now in High School, with an obsession with finding ghosts and he enlists Cassie to help him contact the victims of the train accident.

When he is not searching for ghosts, he plots elaborate pranks against Father James -- a mean-spirited blowhard priest who dominates their parish.  Cassie, who has never liked Father James, finds it amusing but it is very dangerous.  And when Elias gets caught, Father James turns the community against him and he and his family are forced to move away again.  Lonely without her friend, Cassie is determined to continue her search for the ghosts.  Her search comes to an end with a cataclysmic flood.  

An ambitious novel that is loosely based on the life of Saint Eia of the Celts which explores Cassie's search for God and contains a heavy ecological theme.  As a straight story, the plot is a mess, taking significant shifts at several points and drifting between ideas.  That said, the writing is lovely and deep and there are profound moments scattered throughout the book.  It's artistic, but it's a strange read.