This fast-paced thriller begins when a large band of terrorists surrounds and captures tourists visiting the Mayan ruins at Uxmal. Among the hostages are four congressmen who have taken a day off from a Mexican-American conference to see the famed pyramids. Also taken hostage is the CIA's most adept agent, Richard Owen, although the captors have no idea he is other than his assumed identity of a visiting archeologist.

At the White House, President Henry Brendan receives conflicting advice from members of his Cabinet on how to meet the hostage crisis. The secretary of state counsels patience; the national security adviser urges a rapid military strike. Buying time for negotiation is the course the president chooses.

CIA chief Ed Nichols is astounded when he learns that his first choice for an agent to find out what's afoot in Uxmal is already there. To rescue Owen, Nichols assigns another top agent, Emma Thatcher.

Emma has an ally in Owen's longtime friend, a Harvard-educated physician who practices in his native Mayan village near Uxmal. It was he who notified the CIA of Owen's plight and, thanks to lifelong familiarity with the terrain, it is he who leads Emma through the dense jungle surrounding the ruins to where she can survey the layout of the complex, identify Owen's cell, and observes the measures -- including electrified door screens -- the terrorists have taken to secure their prisoners.

While Emma awaits delivery of equipment she has requisitioned from CIA headquarters in Virginia, inexplicable happenings are surfacing elsewhere. The Rembrandt Peale portrait of Thomas Jefferson is found to be missing from the White House. The Lincoln Memorial is cordoned off as men, working around the clock, dig under its foundations. Computer diagrams are stolen in New Jersey. Under cover of night, 40 rubber rafts move to shore from a submarine in the waters off Cozumel.

From here on, the plot is such a web of ploys and counterploys that the sensible reader stops trying to figure out what is going on and lets himself be carried along by the action. We learn the nature of the personal mission that brought Richard Owen to Uxmal and can then understand why, once Emma steals him out of his cell, he chooses to return to it. We watch one congressman die at the hands of a vicious terrorist leader, and later witness a deadly battle fought with giant mining machines deep underground. We are present at Cape Canaveral when the president, there to preside over a space shuttle launch, is targeted for death, and we follow the desperate battle of wits between Owen and the would-be assassin.

Ultimately, all the pieces of the puzzle fall into place in a solution that this reviewer found lacking in credibility. But no matter. "Falseface" is a good read, perfect for a long plane trip or a couple of insomniac nights.

Marilyn Sharp, wife of an Indiana congressman, apparently knows a good deal about CIA resources. She has done her homework on Mayan history, beliefs and structures. What she has not done, possibly by design, is to invest either Richard Owen or Emma Thatcher with distinctive characters or personalities. The two are friendly rivals: brainy, cool, daring and efficient, but enigmatic as to background or motivation. Future books may tell us more; the ending of "Falseface" strongly implies that we will meet these super-agents again.