As hinted at in the title, the one distinctive feature of this plain, quick, decent whodunit is the importance of sign language: the murder victim is deaf--as are some of the suspects. Noah Kendrick, co-owner of a Minneapolis printing plant, is found on the street, dying of stab wounds. His deathbed message--as translated for cop Ryder by Mattie Shayne (a teacher of deaf children who moonlights as an interpreter)--is: ""House burned down. . .No iron man there."" So Ryder and Mattie keep trying to figure out what Kendrick meant as they interview a serviceable batch of suspects: Kendrick's young, sexy, deaf wife (who gets a hefty insurance payoff); his partner, who inherits the business; his ne'er-do-well brother-in-law; his wife's jilted boyfriend; and his best pal, a deaf art-gallery owner. Mattie, pretty and recently divorced, is a rather pallid heroine--despite Hunsburger's dutiful attempts at damsel-in-distress peril and burgeoning romance (with the 50-ish taciturn cop). But, though colorless throughout, this is unpretentious and competent--with a solid solution, an Ellery Queen-ish clue, and the modestly intriguing deaf-world angle.