Q. What is it supposed to be on the show?

A. A cocktail lounge.

 
Q. Where is it supposed to be on the show?

A.  In New York City.

A. In Episode 5 of Season One of Resurrection.
 
Mia (“Lady Vengeance”) is left “murder horny” (to quote Mia and the title of this episode), after her walk & talk with Dexter fails to convince Dexter to share killing a rideshare driver with her, for her amusement.
 
So she goes hunting for a new victim alone .
 
We first see her walking down a Manhattan street at nighttime, wearing a rather flamboyant outfit. She stops at a place with a stylized MG logo near the door and refreshes her makeup while looking at her reflection in the reflective glass door. A doorman assures her that she looks great, and she vainly replies “I know”, before entering the club.


Inside, she immediately approaches an ordinary guy (named Marc)  who is minding his own business. She knows that he will consider himselfI lucky to unexpectedly be hit on by an attractive woman. She buys him a drink before inviting him back to her place.
 
The poor schlemiel takes the bait, and winds up being smashed over the head with a wine bottle, and wakes up tied semi-naked to an X-cross,  with “Lady Vengeance” about to burn his eyes out with lye. 

Q. What is it actually in real life?

A. A cocktail lounge.

Q. Where can I find it in real life?

A. This is unique spot is known as Madam George, located at 45 W 45th St (just off 5th Avenue), in Midtown Manhattan.

 

 

It's hidden behind a small door that would be easy to walk right past, if not for the stylized MG logo.  This small entryway leads to a lengthy set of stairs that takes one down to the subterranean club. [  The name of the bar is most likely taken from "Madame George", a 1968 song by singer Van Morrison, who also gave us “Brown Eyed Girl.” and .“Moondance”. ]     You can find their official website here.

Madame George is often referred to as a speakeasy, mixing 1940s touches with a modern style, and offering a unique selection of cocktails (which are named after various parts of New York) .

Adjectives that come up in the description of this spot include swanky, mysterious, plush, eclectic, nostalgic, and whimsical. 

The lounge features live music to add to the experience.

I was surprised when I later discovered that the earlier scene of Dexter & Mia at the wine bar was actually shot here at Madame George.
 
I had assumed they were supposed to be separate places, and that they had been shot in two different locations, something that seemed to be confirmed by the fact that the parking lot (that was supposed to be just outside the wine bar) was on Lafayette Street (where Dexter & Mia had been walking), while Madame George was two miles to the north, on 45th St. 
 
I assume they were supposed to be two different places, since Mia, a sommelier, refers to the first spot as a wine bar, yet when she enters the second establishment, the first thing she does is to order two rye whiskeys, a hard liquor that wouldn't be available in a true wine bar.  But it turns out that both scenes were shot at Madame George, only from different angles.
 
Here is a StreetView of the door to Madam George: 
 
 

Here is an aerial photo of the location.  And here is a map link.