The Player on the Other Side

"A five-sided card with the letter "J" stamped on it appeared in Robert York's mail, and a day later he was dead, crushed by a boulder. It was no accident. Someone knew York would be under that rock wall at precisely 7:30. Then another card showed up for Emily York, stamped with the letter "H," and Ellery Queen knew he was up against a brilliant killer who made a game of death by warning his victims. The only clue to the murderer's identity was the signature "Y," and Ellery had to find him and stop his remorseless vendetta before "Y" won his mad game."@en
"Ellery Queen tries to find a brilliant killer who warns his victims by mailing them a card signed as "Y.""@en
"A card with the letter "J" on it appeared in Robert York's mail, and a day later he was dead. Then another card showed up, and Ellery Queen knew he was up against a brilliant killer who made a game of death by warning his victims. The only clue was the signature "Y" and Ellery had to find him and stop his remorseless vendetta before "Y" won his mad game."@en
"A playing card inscribed with the letter 'J' appears in Robert York's mail, and a day later he is dead. When another playing card shows up, this one for Emily York, all the police protection in New York can't save her. Ellery Queen knows he is up against a brilliant, twisted killer, one who makes a game of death. But with no clue to his identity, Ellery is in a race against time to stop this remorseless vendetta."