In this collection of mysteries, Agatha Christie presents 12 unexplained phenomena with no apparent earthly explanation, including a dog-shaped gunpowder mark, an omen from the 'other side', an eerie wireless messages and a levitation experience.

The hound of death -- The red signal -- The fourth man -- The gipsy -- The lamp -- Wireless -- The witness for the prosecution -- The mystery of the blue jar -- The strange case of Sir Andrew Carmichael -- The call of wings -- The last seance -- S.O.S.