At last--a novel hinging on the inner life of computers that won't give nonscientific types a headache and won't necessarily insult the intelligence of those already versed in computerese. To start with, McNeil's protagonist is a definite plus: Christopher Webb, a London computer consultant with a provocatively two-sided slant on his work. When Webb is hired to study a commercial computer system, he's out to find potential or actual computer crime--""patches"" in the system that divert dribs and drabs of ""money"" into some clever programmer's own bank account. So Webb's a good-guy detective. But he's also a bad guy because once he unmasks a computer criminal, he finishes up the job by reinstating the illegal ""patch"" and substituting his bank account as the receiver of stolen computer transactions. Neat. Webb's current assignment is huge--one of Britain's biggest bank's computerized ""BANKNET"" system--and slowly, with the surly aid of an exhausted print-out-reading assistant, Webb does turn up a thief--named Alloway. Alloway tries to buy and blackmail him into silence, but when Webb feeds all the information into his friendly neighborhood computer, the computer's advice is ""KILL ALLOWAY."" So Webb does exactly that, as the surely paced plot winds down to a nicely neutral fade-out. McNeil, ""an internationally known computer expert,"" certainly makes convincing stuff of the insider details: how banks decide which computer consultant to bare, precisely how computer centers are set up in unmarked buildings. But he's also a natural storyteller, classy enough to brew a smoky London atmosphere and confident enough in his basic material to let the complications unwind, unhurried and uncluttered. This read-out is highly readable.