Complex sentence: Their plans to destroy Boulder Dam foiled, they proceed, along with Kane, by car to New York City, where they plan to sabotage the launching of a new U.S. Navy ship at the Brooklyn shipyard.
Split into simpler sentences: Their plans to destroy Boulder Dam become foiled, so the group decides to proceed, along with Kane, by car to New York City. Here they plan to sabotage the launching of a new U.S. Navy ship at the Brooklyn shipyard.