COLD LEG

When a retired female Navy combat diver finds a ghost ship carrying nine dead mercenaries and an encrypted beacon from her missing daughter, she must lead a deniable assault on a prison hidden inside a condemned oil rig before the governments behind it flood the whole structure and bury every witness under the sea.
The ship should have been empty.
Instead, it drifts into contested water with its lights dead, its deck slick with blood, nine mercenaries rotting where they fell, and one thing still alive in the silence: an encrypted distress beacon keyed to the daughter Juna Voss has not seen in eighteen months.
Juna walked away from the Navy after a dive accident shattered her team and left her with a private terror she never admitted to anyone. She has spent her retirement fixing boats, dodging old calls, and replaying the last conversation with her daughter, a marine journalist who vanished after chasing a story no one would print.

Now that story is waiting offshore.

The signal leads to a black-site prison built inside an abandoned oil rig beyond any shoreline, any court, any flag worth trusting. Its decks crawl with drones. Its legs are ringed with smart mines. Its cells hold people powerful governments need erased.
To get her daughter out, Juna must lead a strike team through flooded ballast chambers, rusting kill corridors, and a private army that knows exactly who she is.

The rig was built to disappear people.