Penelope Barber

Cassie broke the relay chain on the Acheron, but Vance has spent three weeks planning for exactly that. His answer is the Ascendant - a stratospheric tether rising forty-two kilometres above the East African Rift Valley, above interference, above anything the Vanguard can reach. When the platform hits operational altitude, he can transmit directly to all seven satellites at once. No chain to break.
No train to stop. The window opens in seventy-two hours. Cassie has a rebuilt arm, a plan with a gap in it, and a team that includes the one person Julian has never been willing to destroy: his own daughter. She also has something Julian didn't account for - the valley itself, and a brother who knows every tunnel running beneath it. To end this, she has to climb forty-two kilometres of pressurised cable into the stratosphere and face a man who built his endgame specifically for her arrival.