Complex sentence: After listening to Hassan's demands, Grant disbelieves Hassan wants Jaffa released and instead thinks Hassan engineered Jaffa's capture and plans to use the plane to detonate a bomb loaded with nerve gas over U.S. airspace.
Split into simpler sentences: After listening to Hassan's demands, Grant disbelieves that Hassan wants Jaffa released. Instead, he thinks Hassan engineered Jaffa's capture and plans to use the plane to detonate a bomb loaded with the nerve gas over U.S. airspace.