One black matchbook with a phone number on the cover.

A crinkled receipt for a $100 Negroni.

The faint suggestion of catnip on your tongue.

Those?

Those are some Memento-style clues you’ll use to solve the mystery of the Bassment—a reservations-only blues lounge with a password-protected secret entrance. It’s open now. Somewhere. And here’s the slideshow.

We’ve been sworn to secrecy, but here’s what we can tell you:

1) You’ll have to call 312-386-5778 to learn how to gain access.

2) There’s a perfidious tobacconist who knows more than he lets on.

The inside is like something out of a Mick Jagger fever dream—British flag couches. Gold-wrapped columns. The mural of a nude that’s a cross between Titian and Tim Burton. It’s one of Mick’s stranger fever dreams, to be sure.

They’ll host two bands a night, so bring a date who enjoys the blues. Order some lobster beignets and wash them down with a catnip-infused-tequila drink, because that’s an absolutely crazy thing to do.

Even crazier: the $100 Negroni. It’s made using one of only two bottles of Nolet’s Reserve allocated to the city of Chicago.

You should see the second bottle.