Three universes, Atlantis, time travel, an alternate future or two and a gung-ho gynoid all pull together to give Tom Two-Dan $mith (sic) his next challenge. Being dead doesn't help.
He wakes after an accident in an independent Scotland to find he has mislaid a load of years, his body and a whole universe. He gets trapped in London, devastated by another war. The Mob are in charge, controlling the population, and people are disappearing off the streets.
His investigation goes badly, resulting in him being confined to a stud farm for people, until he escapes and finds out what became of Atlantis.
A liberation force from the US, spoiling to try out some new kit, joins the fray, and very nearly causes another Armageddon.
All this with a headache which may spell the end of him.
One of the problems with hopping between universes is that there is a slim chance you can meet yourself. That cannot happen of course, and so it does, exactly at the point where the whole fabric of space and time collapses.