Complex sentence: At Makepeace's suggestion, Claire purloins the original report on the Cyprus killings with Urquhart's name revealed from the secret government archive where it is stored, but Urquhart's bodyguard, Corder--informed by the archive clerk--seizes the document from her.
Split into simpler sentences: At Makepeace's suggestion, Claire purloins the original report on the Cyprus killings with Urquhart's name revealed from the secret government archive where it is stored. However, Urquhart's bodyguard, Corder--informed by the archive clerk--seizes the document from her.