When a suspense writer can swing out with guts, endearing sarcasm, and raw bravado the way that Tony Kenrick can, the most farfetched plotting can be forgiven--even enjoyed for its sheer outrageousness. ""I doubt you're going to believe it,"" narrator Max Ellis tells us right off. And he's right. After all, Max wants us to believe that the Defense Dept. has developed eyedrops that enable a man to sec in pitch dark but leave him blind during the day. And Max wants us to believe that he's picked to be the guinea pig to test the drops--just because he's a volunteer worker with the blind and because he's still guilt-ridden about blinding his brother (who later committed suicide) in a childhood accident. And Max wants us to believe that the Russians will do anything to find out the secret of the drops, and that a Defense Dept. traitor also lusts for the secret--and will go so far as to hire an eye surgeon to ambush Max and cut out his eyes. (The doctor ambushes the wrong blind man--in an excruciating street scene.) Do we believe any of this? Not really. But once Max is alone in his N.Y. apartment, blind by day and sighted by night, the panic is real enough to steamroller all questions--especially when he loses his cane, runs into traffic, cracks a rib, and is lured by his supposed friends and lover (really Russian hirelings) to Westchester for extended torture, sexual cajoling, and a heart-stopping escape attempt with blind Max at the wheel of a car. Knockdown rough stuff--not for the squeamish--but Kenrick (The Seven Day Soldiers) knows how to keep the atmosphere somehow likable, light, and humane as the nonstop physical abuses hurtle along.