Note to Lloyd Blankfein: Imagine, for a moment, what would happen if a cardiac surgeon were paid like a Wall Street banker in 2006.

For each operation, the doctor would earn more, regardless of the risk to the patient, writes Suzanne McGee in “Chasing Goldman Sachs.” The greater the risk, in fact, the higher the fee. Should half his patients die the next year, the hospital might dismiss the surgeon -- with a golden handshake. He could then take up a post elsewhere or set up his own practice.

“Wall Street doesn’t have to purchase malpractice insurance,” says McGee in this disturbing account of how the big boys ran amok and began blowing up the money grid. “There isn’t even a sense that there is a duty of care to the ‘patient’ -- whether that patient is the client or the financial system.”

McGee, a contributing editor at Barron’s, isn’t out to bury Goldman Sachs Group Inc. or Blankfein, its chief executive officer. Her goal is, rather, to show how Wall Street bankers became preoccupied with their own short-term interests and drifted away from their raison d’etre -- to funnel capital from investors to companies that need it.

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The peril wasn’t that Goldman (Sachs} became “a great vampire squid,” as a Rolling Stone writer so delicately phrased it. The firm actually became something much more dangerous: a seductively successful Pied Piper, luring other banks down a path that led to destruction.

Its profitability was the envy of its peers, McGee writes: Trying to match Goldman’s return on equity was the only way for rivals to pacify their restive shareholders and increase their personal wealth.

This isn’t what Wall Street was built for, she reminds us. The financial system is a public utility, akin to a power company or the water system, no matter how much the comparison makes bankers bristle, she says. Turn the tap, you expect water. Flip a switch, you get light. The money grid works the same way: It connects buyers to sellers and lenders to borrowers, making it possible to raise capital to repair roads and finance companies.

McGee walks us through the trends that led us to this day, notably the shift away from private partnerships, which limited risk. Going public allowed executives to place big bets with other people’s money; it also exposed them to shareholders anxious to match Goldman’s ROE, as the admittedly unpopular Philip Purcell discovered at Morgan Stanley. His ouster as CEO in 2005 reflected his aversion to taking big balance-sheet risks, McGee writes.

“We watched, we listened, and we all learned from that,” McGee quotes one banker as saying.

This is an exhaustive piece of reporting that draws on interviews with some 200 people whose lives are tied to the Street, from hedge-fund managers and venture capitalists to private-equity dealmakers and corporate executives.