Irish isn't all that's lacking. This second entry (after On This Rockne, 1997) in McInerny's latest mystery series just about lacks a mystery, too. True enough, quietus has been put to Hazel Nootin, the least-liked cog in the huge Notre Dame University bureaucracy. But who really cares? To McInerny (director of Notre Dame's Jacques Maritain Center), concern for who-dun-it seems little more than a matter of form, a forced nod in the direction of the genre. Clearly, what gets the author's writerly juices flowing is the chance to deflate some Notre Dame pretensions. Among his targets: religionists (all sects), lay philosophers (all schools), flacks, athletes, grinds, alums, and, of course, academics. Roger Knight, Huneker Professor of Catholic studies, and his brother Philip, the private eye, are back again as McInerny's laid-back sleuthing team. Not that the clues he drops require much in the way of sleuthing, or take up much in the way of space. Precedence goes to a ho-hum football game, an improbable theological conference, and a lifeless romance between a nerdy student and a nubile cheerleader. And to jokes like this: Says a conference planner to his colleague: ""I think Dave could do liaison."" The reply: ""Hey, I'm a married man."" It takes sixty-seven pages for the corpse to turn up, and five minutes or so for the killer to confess. In a murder mystery, that's the definition of perfunctory. Too many characters idling about, too few plot twists. And the wit is as strained as the title's pun.