Complex sentence: However, she understands that her grandfather intended Langdon to decipher the code, which she and Langdon realize leads them to a safe deposit box at the Paris branch of the Depository Bank of Zurich, which Sophie and Langdon go to after escaping the police.
Split into simpler sentences: However, she understands that her grandfather intended Langdon to decipher the code. She and Langdon realize that the code leads them to a safe deposit box at the Paris branch of the Depository Bank of Zurich, which Sophie and Langdon go to after escaping the police.