“If you come inside, I’ll show you my etchings”, she said. She looked at him slyly. 

He didn’t want to see any etchings. But the well known implicit meaning is “if you come in, we can have sex”.

He didn’t want to have sex. But these days, talk of ‘sex’ in public places was usually understood to mean using an illicit iRotic machine together under the influence of hypercoke.

He didn’t want to go in the iRotic or use hypercoke. But since they had discussed this earlier, he knew that she knew that he knew that she didn’t either. Specifically, she had said that she was asexual, and that the most she was willing to do in that direction with anyone was smoke pot and cuddle. So she obviously meant to communicate something like, “if you come in, I will smoke pot and cuddle with you”

He didn’t want to smoke pot and cuddle. But he strongly suspected that she was the spy he was looking for, and so her invitation and the context sure made it look like once inside they might go somewhere very private and exchange important secrets.

He wasn’t in the mood for exchanging important secrets. But he knew that the spy he was looking for was a double agent, and that any apparent invitation to confidential discussion was really an invitation to get shot, inconveniently far from witnesses.

He didn’t want to be shot (though frankly this sounded better than going near an iRotic machine). However he had a concealed stunsword, and was confident that he could best her in combat.

He followed her inside carefully, hand on his weapon.

The etchings were of birds. 

He turned around to smile at her, reeling from the depth of his misunderstanding.

She shot him.