Five weeks after giving birth to our son, I walked into my husband’s office carrying sixty luxury chocolate truffles and Noah strapped against my chest.

The blizzard hit us as we climbed the switchbacks of the Julier Pass.

Visibility dropped to less than ten yards. The wind howled against the chassis of the Mercedes, blowing sheets of white powder across the frozen asphalt. Behind us, through the swirling storm, two sets of high-intensity halogen headlights appeared, relentlessly closing the distance.

"They're using satellite tracking," Julian said grimly, examining his encrypted tablet. "They aren't just following our tail lights. They're tracking the transponder inside the Castiglione ledger itself."

I froze. I looked down at the antique leather satchel in my lap. "The ledger?"

Julian quickly examined the thick spine of the book. With a sharp pocket knife, he sliced through the inner lining of the back cover. Embedded in the hardened glue was a razor-thin, military-grade GPS beacon, pulsing with a faint blue diode.

"They planted this decades ago," Julian muttered, his face pale. "They always intended for whoever found Vault Forty-Two to lead them directly to the private archives in St. Moritz."

"Give it to me," I said.

"Sophie, what are you doing?" Angela warned from behind the wheel, fighting to keep the heavy vehicle from sliding on the black ice.

"Mark," I ordered, turning to the security operative beside me. "Do we have the flare kit from the emergency trunk?"

"Yes, ma'am."

"Give me a magnesium flare and an empty thermos."

I stripped the tracker from the book, dropped it into the stainless steel thermos, jammed the unlit magnesium flare inside, and cracked the window open three inches. The freezing gale screamed into the cabin.

"Angela, on the next hairpin turn, slow down to fifteen miles per hour and kill the headlights for three seconds!"

"Hold on!" Angela slammed the brakes slightly, initiating a controlled slide around a sheer cliff edge overlooking a thousand-foot drop into the Engadin valley.

In that pitch-black second, I ignited the flare, jammed it into the thermos, and hurled it out the window into the deep snowdrift beside the guardrail.

The flare exploded in a brilliant, blinding white glare, illuminating the blizzard like a localized sun and sending the satellite signal into erratic interference.

The lead pursuer—an armored SUV barreling through the blizzard at sixty miles per hour—swerved violently to avoid what their driver likely mistook for our headlights or an explosion. The vehicle hit the icy shoulder, lost traction, and spun uncontrollably, crashing through the guardrail and disappearing into the white abyss of the canyon below.

The second chase car slammed on its brakes, skidding sideways across both lanes, completely trapped behind the snowbank.

Angela accelerated smoothly, guiding our vehicle over the crest of the pass and into the descent toward the secluded valley of St. Moritz.

In the back seat, Noah cooed softly, reaching out his small hand to touch my cheek. I kissed his tiny fingers, my heart beating with feral, maternal resolve.