Is there a barrier that divides the dark unknown from the everyday world around us?
If so, is it broken sometimes by the dead returning, by the undead, or by alien creatures?
What else could account for the chance meeting (or was it?) between a young student and hitch-hiker who turns out to be so much stranger than she seems?
Why else should three successive crews flying a Second World War bomber - Blackham's Wimpey - be driven to madness, despair, even to death, though the plane returns from each mission without a scratch?
Who are Fred, Alice and Aunty Lou; the figments of Peter's imagination that become a real life nightmare for Roger and Biddy?
There is St Austin Friars, too: a church without a congregation - until a burial service, oddly arranged a month ahead, is attended by a sinister assortment of the living and the dead. And Sergeant Nice, an ordinary policeman in an ordinary seaside town faced with a series of quite extraordinary thefts; the work surely, of no human hand.
Chilling, but often humorous as well, these stories creep up on you and take you by surprise.