Trouble's afoot at N.Y.C.'s Irish Cultural Center, where retired history professor Brian Donodio--on his first day teaching a survey course--meets a purple-haired punk named Melisande and gets a mysterious please-can-we-meet note from visiting Irish cop Maureen Sullivan. Brian soon discovers Maureen's dead body, is interrogated by Detective ``Con'' Connolly of the NYPD, then warned not to snoop by his own daughter, Deirdre, a field agent with the INS. Brian, of course, pays no attention to her, but while Con and Deirdre are initiating a sweet romance, he stumbles on the Cultural Center director snorting coke and learns that Maureen's sister Monica, who had preceded her to the States, is missing--and Maureen had been searching for her. More bodies pile up before Brian heads for Ireland to see whether the root of the troubles lies with the IRA, drug-runners, or a forged green-card operation. Con and Deirdre will fly to Donegal just in time to rescue Brian from an infamous gang of criminals. Undemanding first-mystery fare from children's author Callahan, whose culprits are, alas, less believable--and engaging- -than the Donodios and Con.