SO LONG AT THE FAIR (212 pp.) Anthony Thorne Random House ($2.50)
"Rooms 38 and 39," says the smiling desk clerk at the Paris hotel, handing over the keys; "you have come to see our great Exposition?" Vicky Barton and her brother John take the keys, sign the register, climb the red-carpeted stairs to their rooms. To Vicky's horror, next morning, both John and Room 39 are gone.
"Yes, Mademoiselle?" asks the desk clerk, giving Vicky a fishy stare. "What has become of Monsieur Barton, your brother? But how should we know, Mademoiselle? Mademoiselle herself ought to recall that...