A hidden network sustains our world, but it's no longer safe.

Every button, house, nation and financial market depends on a massive, unseen web of cables across the ocean floor. Power cables and pipelines on the seafloor provide the world with energy. This is the newest battlefield where countries must protect their interests - and the functioning of daily life - while rivals test their limits. From the Baltic to the Pacific, sinister ruptures, mysterious vessels and submarine incursions mark a conflict already under way.

With gripping accounts of maritime patrols and access to naval officers, undersea engineers and cable operators, Elisabeth Braw captures the fragility of an infrastructure that underpins everything from mortgages to cancer research and the global financial system to simple emails.

The stakes are immense. Virtually all global internet traffic runs through these arteries, and energy runs in cables and pipelines alongside them - yet the more essential this network becomes, the more exposed it is. The Undersea War shows that the next great conflict may not erupt on land - but in the depths below.