Honestly thought this was the collection when I ordered it from the library, but no, it's just the novella itself. Lamb orders Ho to carry out an unusual assignment, and Ho wonders what things would be like if he'd never been around. Slough House has a visitor. The Slow Horses plan on having Christmas drinks. Without Ho. Short, sour, festive, scabrous, but does clear up something of a long-running cliffhanger as a reward to constant readers and a consolation, presumably, because Herron's next isn't a Slough House book, and waiting for the book after that would be a bit much even for Lamb. Well, no, not him. But still.