"I am an albino," Beowulf Shaeffer, the narrator of the novelette, says of himself.

"An underground civilization and point six gravities have made of me a pale stickfigure of a man, tall and attenuated," he says. He does not look much like a daring adventurer, and he does not think of himself as one. He just does what he thinks he must. In the case of "The Borderland of Sol," he pilots Sigmund Ausfaller's ship as a way to get to earth to be with his wife and children. He is an entertaining narrator, focusing on the action and speaking with a dry, understated wit, as when Julian Forward asks: "Shaeffer, what does a professional pilot think when his hyperdrive motor disappears?" Replies Beowulf, "He gets very upset."

Beowulf is also very good at explaining why some possible solutions to the mystery of the...