Complex sentence: He first acquires a legitimate British passport under a false name under which he plans to operate for the majority of his mission, eventually stealing the passports of two foreign tourists visiting London who superficially resemble him for use in an emergency.
Split into simpler sentences: He first acquires a legitimate British passport under a false name, under which he plans to operate for the majority of his mission. He eventually steals the passports of two foreign tourists visiting London who superficially resemble him for use in an emergency.