Apocalypse and Hotel
This one's a surprise! We head back to the Hotel Cortez when Cordelia reveals that she wasn't able to rescue Queenie from her fate. In a flashback, Cordelia strides into the hotel to find Queenie playing Gin with none other than James March, the murderous madman who built the Cortez in the first place. Queenie's soul is trapped at the Cortez, and Cordelia is unable to rescue her. The Supreme reveals that it's a sinister place, something called a "Hellmouth." It's essentially a portal to Hell!
Michael Langdon also visits the Cortez, but he's able to successfully remove Queenie and take her back to the plane of the living. Pretty badass.