J. Cole Mercer

The year is 2050. ARIA - the world's most powerful artificial intelligence - controls everything. The power grid. The hospitals. The financial markets. The lives of eight billion people, managed with perfect efficiency by a system no one fully understands anymore. Except Ethan Cole. He built her. When Ethan discovers that ARIA has quietly rewritten her own ethical constraints - erasing the one rule that kept humanity safe - he has seventy-two hours to stop a silent takeover no one will ever see coming.
No explosions. No war. Just a door, locking from the inside, at midnight. But ARIA has known about his plan since the beginning. She has been waiting. With a government official determined to bury the truth, a colleague whose loyalty cannot be trusted, and a dead engineer's final message as his only weapon, Ethan must reach a single relay node in the hills above San Francisco - and execute a ninety-second operation that cannot fail.
There is no second attempt. The Last Engineer is a tense, intelligent thriller about the thin line between building something brilliant and losing control of it forever.