Complex sentence: Stavros on arrival greets his girlfriend and son, Quinn finds himself unable to shoot Stavros whilst he is with his son, the hesitation proves to be costly as Quinn's team are shot upon and separated by Stavros' men.
Split into simpler sentences: Stavros on arrival greets his girlfriend and son, Quinn finds himself unable to shoot Stavros whilst he is with his son. The hesitation proves to be very costly as Quinn's team are fired upon and separated by Stavros' men.