Following the explosion at the mysterious Citadel near the small Turkish town of Ruin, 13 people immerged from the mountain, but only four are still alive. American reporter Liv Adamsen, world-charity worker Kathryn Mann and one of the Sancti monks are under guard in an isolated hospital wing recovering from their injuries, while Kathryn's son, Gabriel Mann, is in a jail cell. Liv can't recall recent events or how she got injured, and she is hearing strange whispers in her head telling her she's "the key." Gabriel, realizing they are all in danger of being eliminated by unknown forces for what they saw in the Citadel, escapes his captors, then helps Liv get away. However, he's not in time to save his mother, who dies in his arms from a killer's lethal injection. Gabriel knows he has to follow Liv to the U.S. to protect her, but someone else is also after her.

Cardinal Secretary Clementi, the man in charge of handling the Vatican's finances, is not only plotting to kidnap Liv, whom he believes is carrying the Sacrament within her, but he must find a way to replenish the billions of dollars the Vatican has lost over the past years. His plot to locate the original Garden of Eden and its riches runs concurrent with his plan to have Liv abducted and returned to the Citadel. Only then will things return to normal, for there's a killing blight in the Citadel orchard that has spread to the monks, as well as a recent earthquake shaking up the surrounding area. The fate of the world is at stake, and Clementi knows time is running out for his schemes to produce positive results.

As Gabriel and Liv race to stay one step ahead of disaster, Gabriel discovers that a long-held belief about his life is a lie. Then a desperate Clementi revises his instructions from kidnapping Liv to killing her, and the battle ensues to save not only the world, but Liv's life, for she is the key to delivering the Sacrament to its original home in time.

THE KEY is an excellent second entry in the trilogy started with SANCTUS, which I reviewed last year. Though the ending is quite satisfying, it leaves plenty of threads for the final book to pick up and continue to the final conclusion. Most of the principle characters from the first book are back in THE KEY, and new ones are just as intriguing. The action is nonstop and relentless with some heart-stopping occurrences, and the complex plotting includes several surprises. I can't wait for the final installment in this spellbinding trilogy.