They understood nothing. That was not claustrophobia. That was logic, survival instinct, an IQ test. Anna sniffed, an exclamation remarkably close to "harumph."

Lisa looked up with limpid gray eyes, the tails of her braids brushing Anna's boot tops. "Too tight?" she asked, and reached to adjust the buckle that cinched the webbing around Anna's upper thigh and under her buttock.

"No," Anna said, and, with an effort, "Sorry."

Again the acceptance. Again the total lack of understanding. Apparently idiosyncratic behaviors were not cause for comment in the caving community.

"You'll want it tight," Timmy said. "Once you get your weight on it things loosen up considerably."

Anna knew that. But for the pack, the gear was familiar. Climbing equipment: seat and chest harness, locking carabiners, rappel rack, Gibbs ascenders, D-ring, JUMAR safety. All the chunks of metal and rope intended to keep a caver in one piece on the way down and on the way back up. From a lifetime's habit of safety, Anna watched as each link was forged in the chain of devices designed to defy gravity.

Letting Timmy and Lisa tell her things she knew, dress her as if she were a baby, she contributed little. Much of her brain was given over to a jumble of dangerous thoughts, dangerous because a preoccupied climber can very easily become a dead climber. A moment's inattention, an unclosed D-ring, an improperly threaded rack, an unlocked carabiner, and suddenly the whole house of cards-and the climber- comes tumbling down.

Anna longed to call her sister, Molly, to talk about friendship and irrational fears, duty and human frailty. Since there was no time for a chat with her personal shrink, she went through her mental files and pulled out everything she could remember her sister having said about coping with phobic reactions. Desensitization, the slow increasing of exposure to the feared situation; no time. Relaxation exercises. Anna snorted, and Lisa and Timmy stopped what they were doing to look at her expectantly.