Detective and widow, a thriller?

He was a homicide detective (cop/officer, whatever strikes your fancy) sent to investigate her husband's murder. He was seasoned and hardened (drinks?), and he didn't expect to be fascinated with her. A mourning widow in need of protection... Or not. Because his instinct is telling him something that no one else noticed. There's something strange about her, could she be faking? Will there be other murders? What would happen if she figured that he is suspicious? Run, seduce him, kill him too? Is it all in his mind? Whether this is noir, modern or somewhere in between this should be interesting...

I imagine that she could be a gold digger carefully hiding her cleverness, or more openly superior to many men (think a well known shrink?). Neither of them would be teenagers or anything. I can see her mid 20s to mid 30s, and him 30 to 45? She being slightly older than him would be ok for me if it makes sense.

Read my yes/no in my signature, and please write at least 1 post a week - pms or emails/Google doc. Do NOT contact me if you "are not able to do long posts". I'm writing the female. We can both handle the NPCs, family members, policemen, whatever, but this will NOT be a smut fest. He's not looking for an affair, and she's not fucking all his colleagues (if she has to resort to seduction sometimes it's one thing, but it certainly won't be central). Looking for a noir or modern setting somewhere on Earth LOL. Big gritty city, or him being sent to investigate in a small, closed-off, tight knit village? We could imagine two dominants or two very strong switches, both leading the other on in a desperate attempt to find out what they really know? Trained to win, strong personalities and egos. It's obvious that sometimes he'll get "on top" (no pun intended?) and sometimes she will. Not looking for a cutesy comedy or a villain just turning out to be misunderstood... Doesn't have to end in tragedy but certainly won't be a romcom.

Please come with ideas about your character and if possible more.