A book about the Enron Corporation and its scandalous collapse, just signed at Doubleday, will be coauthored by a key player in the drama whose name, for obvious reasons, cannot be disclosed at present. The executive editor of the house's Currency imprint, Roger Scholl, signed the book, tentatively titled Power Failure, from agent David McCormick at IMG, for U.S., Canada, open market and second serial rights. The author who can be named is journalist Mimi Swartz, who is based, like the unhappy company, in Houston and has excellent sources on the story; she has written for the New Yorker and Texas Monthly. Scholl hopes to publish early in the fall.