The first dive of the project was purely one of exploration, to see firsthand the effects of the crud so she and her fellow marine scientists on board the nearby research ship could evaluate the full scale of the problem and create a precise pattern for future study of the cause.

The first brown crud invasion warning had been sounded by a commercial diver working off Jamaica in 2002. The baffling crud had left a path of underwater destruction unseen and mostly unreported from the surface as it drifted out of the Gulf of Mexico and around the Florida Keys. That outbreak was, Summer was beginning to discover, much different than here. The crud on Navidad Bank was far more toxic. She began to find dead starfish, and shellfish such as shrimp and lobster. She also noted that the fish swimming through the strange discolored water seemed lethargic, almost comatose.

She removed several small glass bottles from a pouch strapped to one thigh and began taking water specimen samples. She also collected dead star- and shellfish and dropped them in a netted bag attached to her weight belt. When the jars were sealed and securely resting in the pouch, she checked her air again. She had over twenty minutes of dive time left. She rechecked her compass readings and began swimming in the direction from which she had come, soon reaching clean and clear water again.

Casually observing the bottom that had turned to a small river of sand, she sighted the opening to a small cavern in the coral, one she hadn't noticed before. At first glance it looked like any one of twenty others she'd passed in the last forty-five minutes. But there was something different about this one. The entrance had a square-cornered, carved look about it. Her imagination visualized a pair of coral-encased columns.

A ribbon of sand led inside. Curious, and with an ample supply of air in reserve, she swam over to the entrance of the cavern and peered into the gloom.

A few feet inside the chamber the indigo of the walls flickered under the shimmering light from the sun's rays above. Summer slowly swam along the sandy bottom as the blue turned dark and became brown after several yards. She nervously turned and looked over her shoulder, reassuring herself at seeing brightness surrounding the opening. Without a dive light there was nothing to see and it didn't take great imagination to picture danger in the inky interior. She nimbly turned and stroked toward the entrance.

Suddenly one of her fins brushed against something half buried in the sand. She was about to simply dismiss it as a lump of coral, but the coral-encrusted object had a seemingly man-made symmetrical contour. She dug into the sand until the thing came free. Moving toward the light, Summer held it aloft and lightly swirled it in the water, cleaning away the sand. It looked to be about the size of an old-fashioned lady's hatbox except that it felt quite heavy, even underwater. Two handles protruded from the upper area, while the bottom gave the impression under the encrustation of having a pedestal base. As near as she could tell, the interior looked hollow, another sign that it wasn't created by nature.

Through the mask, Summer's gray eyes mirrored skeptical interest. She decided to carry it back to the habitat, where she could carefully clean and determine what was to be seen under the accumulated coral sea growth.

The extra weight of the mysterious object and the dead sea life she had collected on the bottom had affected her buoyancy, so she compensated by adding air to her BC. Tightly gripping the object under her arm, she languidly swam toward the habitat oblivious of her air bubbles trailing behind her.

The habitat that she and her brother would call home for the next ten days appeared through the shimmering blue water a short distance ahead.

Pisces was often called an "inner space station," but she was an underwater laboratory designed and dedicated to ocean research. She was a sixty-five-ton rectangular chamber rounded off on the ends, thirty-eight feet long by ten feet wide by eight feet high. The habitat sat on legs attached to a heavy weighted base plate that provided a stable platform on the seafloor fifty feet below the surface. The entry air lock served as a storage unit and a place to don and remove diving equipment. The main lock that maintained a differential pressure between the two compartments contained a small lab working area, a galley, a confined dining area, four bunk beds, and a computer and communications console connected to an outside antenna for contact with the world above the surface.

She removed her air tanks and connected them with a bottom tank filling station next to the habitat. Holding her breath, she swam up and into the entry lock, where she carefully set the pouch and net containing her specimen samples in a small container. The mysterious coral-encrusted object she set on a folded towel. Summer was not about to risk the dangers of contamination. Suffering from the tropical heat and the sweat emerging from her insulated pores for a few more minutes were a small price to pay to avoid a potentially deadly illness.

After swimming in and through brown crud, one drop on her skin could prove fatal. She did not dare remove her Viking dry suit with attached Turbo hood and boots, gloves sealed by locking rings and full face mask, just yet. After unsnapping her weight belt and buoyancy compensator, she turned on two valves that activated a strong sprinkling system, washing down her wet suit and gear with a special decontamination solution to remove any brown crud residue. Certain she was properly sanitized, she turned off the valves and rapped on the door to the main lock.

Although the masculine face that appeared on the other side of the view port belonged to her twin brother, there was little resemblance. Though they were born within minutes of each other, she and her brother Dirk Jr. were about as nonidentical as twins could get. He towered over her at six feet four, and was lean and hard and deeply tanned. Unlike her straight red hair and soft gray eyes, the thick mass of hair on his head was wavy and black, the eyes a mesmeric opaline green that sparkled when the light hit just right.

When she stepped out of the chamber, he removed the yoke and collar seal between the neck of her suit and head mask. By the look in his eyes that were more piercing than usual and the grim expression on his face, she knew she was in big trouble.

Before he could open his mouth, she threw up her hands and said, "I know, I know, I shouldn't have gone off alone without a dive partner."

"You know better," said her brother in exasperation. "If you hadn't sneaked off at the crack of dawn before I was awake, I would have come after and dragged you back to the lab by your ear."

"I apologize," said Summer, feigning remorse, "but I can accomplish more if I don't have to be concerned with another diver."

Dirk helped her undo the heavy, riveted waterproof zippers on her Viking dry suit. First removing the gloves and pulling the inner hood down behind her head, he began peeling the suit from her torso, arms and then legs and feet, until she could step out of it. Her hair fell in a cascade of copper red. Underneath, Summer wore a skintight polypropylene nylon body suit that nicely displayed her curvaceous body.

"Did you enter the crud?" asked Dirk with concern in his tone.

She nodded. "I brought back samples."

"You certain there was no leakage inside your suit?"

Holding her arms over her head, she did a pirouette. "See for yourself. Not a drop of toxic slime to be seen."

Pitt put a hand on her shoulder. "Words to remember: 'Don't ever dive alone again.' Certainly not without me if I'm in the neighborhood."