"Generally speaking the dead do not return," pronounced Antonin Artaud. But the dead are permitted to visit those who welcome them. Their spectral, machine-made voices echo in deep tunnels under London. Voices without hosts. Without agency. They make their oracular pronouncements even when nobody is listening on the vast empty platforms of the Elizabeth Line. They have their codes and their secret meanings.

Four stories starting everywhere and finishing in madness. Four acknowledged guides. Four tricksters. Four inspirations. Algernon Blackwood. Arthur Machen. J. G. Ballard. H. P. Lovecraft. They are known as "Agents of Oblivion". And sometimes, in brighter light, as oblivious angels . . .

As host, as oracle, Iain Sinclair moves through this quartet of tales, through a spectral London that once was, or might never have been.