Niven uses an edgy banter among his main characters to lighten his novelette's tone. For example, after Sigmund has provided Beowulf and Carlos with some James Bond-like gadgets (including buttons with, as Sigmund explains, a "Sinclair molecule chain," strung between them— "It will cut through any normal matter, if you pull hard enough"), Carlos asks Beowulf: "Have you thought of anyone you'd like to use that magicwire on?"

"I've been making a list. You're at the top."

"Well, watch it. Sigmund knows you've got it, even if nobody else does."

"He's second."

The humor helps ease the effect passages explaining the science of the novelette can have on the pace of the narrative. In this case, the banter sets up an explanation of black holes: The theory of the black hole wasn't new to me, though the math was over my head. If a star...