Actually, ``ardent'' doesn't begin to describe Brian Herrick, late keeper of Marsh's Library in Dublin, a man so cloaked in the mantle of Jonathan Swift that everybody calls him ``The Dean''; deputy keeper Charlotte Bing is convinced that when he's in his cups, he thinks he is Swift. And Herrick had been in his cups more and more often in the months before his fatal poisoning, as he gathered his Gulliver-themed cronies-- Lilliputian cabaret dancer Joneux Ariane Danvers-Forde, Brobdingnagian library conservator Jan deKuyper, Yahoos Teddy and Bunny Baer (the comic stripper and her doorkeeper husband)--in various permutations for his ``Frollicks,'' videotaped dramatizations of Swift's most ribald verses. Herrick's unsparing death scene, coming at the end of such an evening, has been memorialized on videotape too. Chief Supt. Peter McGarr (Death on a Cold, Wild River, 1993, etc.) juggles suspects who seem as grotesque as their Swiftian originals while his staff--special honors this time to Supt. Hugh Ward and Insp. Ruth Bresnahan, whose efforts eclipse McGarr's--sort out rumors of blackmail, theft, and period forgeries. Gill's Dublin is as rich and reeking as ever, though the story peters out unforgivably in a blaze of squibs. Lacks the inevitability of its companion piece, the masterly Death of a Joyce Scholar, but combines the brainy and the earthy with Swiftian panache.