Can anyone tell me what happened in FMA: Brotherhood?

A scar faced man kills a state alchemist.The Elrics see Shou T. and study living creature transmutation while playing with Shou's kid Nina and dog Alex.Going back to study they see a chimera Shou made.Ed finds out its Nina and Alex.Mad,Ed nearly beats Shou to death,only stopped by Al.The scar faced man kills Shou and the chimera