Lethbridge-Stewart - The Grandfather Infestation: A Doctor Who spin-off novel.

The late 1960s and pirate radio is at its height.

Something stirs in the depths of the North Sea, and for Radio Crossbones that means bad news.

Lethbridge-Stewart and his newly assembled Fifth Operational Corps are called in to investigate after the pirate radio station is mysteriously taken off the air, and a nuclear submarine is lost with all hands.