Anthony Trollope's Christmas at Thompson Hall

She dropped the beard very softly -- and there on the pillow before her lay the face of a stranger.  She had put the mustard plaster on the wrong man.
--Anthony Trollope, Christmas at Thompson Hall (Penguin, 2014)

Trollope's story was originally published in The Graphic, Christmas Number, 1876.  I don't always think of Trollope as particularly funny, though he is often droll in a serious way, but in this story his droll observations are accurate but structured in a particular manner to make them extraordinarily amusing.  Mr. and Mrs. Brown are in Paris on a very cold night in Dec. and Mr. Brown is balking at getting home to Thompson Hall in time for Christmas.  "She had perceived that as her husband became really ill he also became more tractable and less disputatious."  As they go to bed he insists that she find a jar of mustard and apply it to his throat so he can get some relief.  She has some amusing misadventures as she searches through the dark hotel for the mustard and then, after applying it, realizes it is the wrong man:
Not Priam wakened in the dead of night, nor Dido when first she learned that Aeneas had fled, not Othello when he learned that Desdemona had been chaste, not Medea when she became conscious of her slaughtered children, could have been more struck with horror than was this British matron as she stood for a moment gazing with awe on that stranger's bed.

The Browns' room was 333 and she had entered 353:  Remarking to herself, with a Briton's natural criticism of things French, that those horrid foreigners do not know how to make their figures, she rushes back to her room.  She tells her husband she lost her way:
"Where have you been all night?" he half whispered, half croaked, with an agonizing effort.
"I have been looking for the mustard."
"Have been looking all night and haven't found it?  Where have you been?'"
But she can't tell her husband what happened.  After all, she had been in another man's bedroom.  They must fly as early as possible from the vengeance of the man she injured.

But she was caught and reported before they could leave; her name was on the handkerchief she had used. After much arguing and threats to call the police and complaining by the victim, Mr. Jones -- "It seems to be deuced like a practical joke" -- they all reconcile, up to a point, and leave the hotel.  They all end up on an omnibus, a boat and a train uneasily together, all three eventually arriving at Thompson Hall on Christmas.  Mr. Jones, it turns out, is to marry Mrs. Brown's sister, to whom Mrs. Brown confesses everything. A member of Parliament, present at the Christmas festivities, sums it up by saying,  "you should never go to bed in a strange house without locking your door."