The 6th Target - James Patterson

When a lone gunman goes on a shooting spree aboard a packed San Francisco ferry, Lieutenant Lindsay Boxer is called in to investigate. At the scene she finds three people dead and Claire Washburn fighting for her life. Lindsay promises to find whoever did this. But it's a promise she may not be able to keep.As the investigation makes its way to court, news of a child abduction comes through. Lindsay discovers that more children have been taken. But with no ransom demands the abductions don't seem to make sense - unless the kidnappers aren't planning on returning their hostages... The clock is ticking as Lindsay tries to fit all the pieces together. She knows that if she doesn't find the children quickly it will be too late...