>>>or his attention turns to her.
Burying the story hook. This is the most interesting feature of the premise. The relationship of the killer with the detective is a stronger pitching point than the relationship with the NYC cop.
And a New York cop has no legal authority in London. He certainly can't make an arrest. And police are quite territorial about an outsider, in this case a foreigner, meddling in cases in their jurisdiction, So why is he even there?
Whatever, the logline places the relationship problem ? the ?Odd Couple? ? before the plot problem, apprehending a serial killer. In a logliine, the plot takes precedence.
>>>some very nasty habits
Don't they all? Isn't serial killing a nasty business to begin with? IOW: be specific. What is the distinguishing feature that differentiates this killer from others? That has a foreigner meddling in the case?