They went aboard the alien ship that had showed up at their hostel on the moon.
Harriet and two other women, and six men counting the guide and Weaver. The ship was a red-lit cavern. The "crewman" turned out to be a hairy horror, a three-foot headless lump shaped like an eggplant, supported by four splayed legs and with an indefinite number of tentacles wriggling below the stalked eyes.
"They're more like us than you'd think," said the guide. "They're mammals, they have a nervous organization very like ours, they're susceptible to some of our diseases -- which is very rare -- and they even share some of our minor vices." He opened his kit and offered the thing a plug of chewing tobacco, which was refused with much tentacle-waving, and a cigar, which was accepted. The creature stuck the cigar into the pointed tip of its body, just above the six beady black eyes, lit it with some sort of flameless lighter, and puffed clouds of smoke like a volcano.