Bridge of Clay by Markus Zusak (Knopf) Imagine five young brothers — a mother who is dead and a father who has departed – sharing a home, trying to find their way through life, with beers cooling in the fridge, a weighty secret, and a mule that regularly inhabits the kitchen. These are the Dunbar boys, whose sweeping story is told in Markus Zusak’s long-awaited novel, “Bridge of Clay,” a 500-page emotional roller-coaster. The boys create their own pain to relieve the hurt of abandonment, but none more so than Clay, the next to youngest Dunbar, who runs to escape, who is in constant training for some undefinable future event.