Visibly distressed, Calladine blurts out a fantastic tale of having attended a ball at the Semiramis Hotel the night before, and having met a young woman dressed in a distinctive masquerade costume who had early the next morning turned up unannounced at his chambers seeking sanctuary.

Hanaud and Ricardo accompany Calladine across town to his chambers, and initially conclude that he imagined the whole thing when they discover that he is a user of the drug mescal, known for its ability to create colourful hallucinations.

With the assistance of the director of the Opera House, Hanaud gets Joan Carew to sing her role in that night's production dressed in the distinctive costume she was wearing when she had disturbed the thieves.

[1] Several of his previous novels had been adapted for the silent screen, and he started work on a purpose-written screenplay for a proposed film to be called The Carnival Ball.

[2] This never materialised, but Mason reused many of the ideas within it, initially with a view to incorporating them into his novel The Summons on which he was then working, but eventually publishing them as a separate long story/novella The Affair at the Semiramis Hotel.