Complex sentence: Alex was able to prove her innocence in the Grand Central Terminal bombing with the help of her classmates at Quantico and discovered that the suspected bomber was former FBI analyst-trainee Elias Harper who had planted the bomb under the instruction of a mastermind terrorist.
Split into simpler sentences: Alex was able to prove her innocence in the New York bombing with the help of classmates from Quantico. She discovered that the suspected bomber was former FBI analyst-trainee Elias Harper, who had planted the bomb under the instruction of a mastermind terrorist.