Complex sentence: Seizing the opportunity, Dixon threatens to cause trouble for Viktor's friends, most seriously by deporting Gupta back to India, where he is wanted for assaulting a corrupt police officer back in 1979.
Split into simpler sentences: Seizing the opportunity, Dixon threatens to cause trouble for Viktor's friends. Most seriously, he plans to deport Gupta back to India, where he is wanted for assaulting a corrupt police officer back in 1979.