Jordan Sofer’s sixteen-year-old daughter appeared in his office crying one rainy Tuesday in March, sparking a chain of events that sent his life’s trajectory hurtling down a long, serpentine fuse toward a powder keg.

Jordan, Helion Engineering’s Director of Cartographic Solutions, sat at his workstation in a San Francisco office tower, correcting a topographic map of Costa Rica’s Arenal volcano. An intern had used 2005 elevation data, which didn’t account for the height added in 2010 when molten rock last spewed from Arenal. “You need a little boost,” Jordan said aloud to the volcano rendered on his display.

As he redrew contour lines, Jordan became aware of muffled sobs behind him. Millie huddled on the floor in the corner, her knees, naked under her short denim skirt, drawn to her chest.

She hadn’t used the door. Whatever made Millie cry had also filled her with the familiar, overpowering urge to draw.

“What happened?” Jordan glanced out the vertical glass panel beside his office door to the hallway, empty except for framed antique maps on the walls. No one had seen Millie materialize. He knelt beside Millie and kissed the top of her black-haired head, pushing the soft curls she inherited through Carole’s Haitian ancestry from her light-skinned forehead, the genetic contribution of Jordan’s Eastern European Jewish heritage. Millie smelled fresh, like honeydew. Her tears dampened Jordan’s blue Oxford shirt, leaving translucent streaks in the cotton.

“Tyler,” she said. “After school, he said if he couldn’t have me, no one could. Ben caught up to us and Tyler started shouting. I ran to tell Mr. Kramer. Then into an empty classroom.” Jordan felt for her index finger, still tacky with blood.

Millie didn’t have to tell Jordan what happened in that empty classroom; he’d have done the same if he feared for his physical safety. He pictured Millie searching for notebook paper, or perhaps cardboard, an index card, a discarded paper bag, anything on which to draw. Then rummaging for a pen, or a pencil, chalk, crayon, anything to mark that surface.

In Millie’s highly agitated state, details poured from her memory with photographic accuracy. She drew, as she could only when desperate–without training, without straight edges, protractors, compasses, CAD programs or reference materials, without erasures or strike-throughs–a professional-quality floor plan of her father’s office. A place she’d been before and felt safe. She’d pricked her skin, closed her eyes, and laid her bloody finger on the map.

Jordan tapped his iPhone. His son, Ben, Millie’s twin, answered on the second ring. “Where are you?” Jordan asked.

“Home,” Ben said, his mouth full.

He’d be in the kitchen of their San Carlos house, on a quiet hillside twenty-five minutes from downtown San Francisco, in front of the open side-by-side refrigerator. Pouring cornflakes into his mouth straight from the box. Washing them down with milk straight from the plastic gallon jug.

Carole would have made Ben get a bowl. After Carole succumbed to breast cancer four years ago, Jordan became lax about minor rules infractions. A single parent had to pick his battles. With Ben, Jordan dumped all his discipline points into one bucket: listening. The kid’s ears, like broken antennae, seemed unable to tune to the frequency of Jordan’s voice.

“Millie’s here,” Jordan said. “You okay?”

“Kramer came out before Tyler could slug me. He’s suspended for three days. It sucks having to stand up to bullies instead of just teleporting the hell out of there, like some people I know.”

Always with the barbs, that kid. The who-cares attitude worn like a flak jacket, envy smoldering underneath. Why did it always have to be fraternal twins, a boy and a girl, one with the ability, one without? Ben was so much like Jordan’s twin sister, Sarah. They both lacked what the family called the “Cartographer Gene” though its origins, whether in biology or something more arcane, were obscure. And they both resented their siblings and parents’ power. Jordan wondered whether all “Cartographer” families–the population’s tiny fraction across all races and ethnicities believed to have this trait —- experienced the same fractured dynamic.

He deflected Ben’s remark, finding it much easier to keep Ben at arm’s length than to engage.

“We’ll be there soon,” Jordan said.