Spoon on the Wall

I feel the 'undercover policewoman' needs a descriptor for her personality, or for her past. 'Lures... into a sexual relationship' sounds a little menacing, perhaps you could make this sound more procedural, while solidifying that this must be done to bring down the drug dealers.

I would introduce the ending to your logline first, then introduce the policewoman, then explain her objective.

Here's an example: Infiltration of a cocaine trafficking ring relies solely on the undercover mission of an inexperienced policewoman, involving a false love interest in a violent and ambitious member of the Albanian mafia.