This was no longer a cave. From here on, it was a man-made tunnel, and not an old mine, either. This was recent work, and judging from the perfect, curling symmetry of the grooves, it had been done by an unusually precise machine. No, this was not a mine, but it might be an explanation for why the hybrids could disappear in one place and reappear in another. Too bad that the ground-penetrating radar he had ordered had been so slow in coming. No question, it would have taught him a lot.

To be certain that there was absolutely no light at all, he stuffed the light stick in his pocket, then waited with his eyes open, staring into the sparks generated by his own nervous system.

No light at all, and absolute silence as well. A little water dripping back in the natural cave, that was all.

Going back was out of the question, so he only had two choices, stay here or move on down the tunnel, but before he moved deeper, he had another piece of business to attend to, and not a pleasant one.

He opened his shirt and felt his chest until his fingers were over the slightly stiff area an inch below his right nipple that marked the spot where his tracking implant had been injected. He unsheathed his knife and isolated the object between the index and middle fingers of his left hand. He worked in the dark. No light was needed, and all light in a place like this was a risk, always. There was a procedure for doing what he was about to do, and he’d trained on it, so he didn’t need to see. It had been anticipated that a man might at times need to get rid of a rescue transponder.

A pulse of agony raced up into his neck and down into his gut as he slid the tip of the blade into his skin. Pressing it deep, he choked back the desire to groan. As he had been taught, he raised the blade until the implant was between it and the surface of his chest. Now he changed the angle of attack, so that the tip of the knife was behind the object. Drawing the blade back, he slowly pulled the implant out with it.

By the time he finally had the thing in his hand, he was experiencing some pain-induced vertigo. Taking deep breaths, he felt into his service medical pack for a patch, pulled one out, and slapped it over the wound, which was raining blood.

He held up the light stick to regain his bearings. Rather than leave the remains of the implant behind as evidence, he crushed it between his teeth and pocketed the debris.

As he went along the downsloping passage, he began to hear a sound ahead. He listened. Was that a voice? Somebody singing?