Eleven stories of adventure, exploration, and extreme zoology as humanity discovers there are things that bump, growl, and bite in the dark. Stories include:
- The Iguanodon (1882) Robert Duncan Milne
- The Monster-God of Mamurth (1926) Edmond Hamilton
- Bells of Oceana (1927) Arthur J. Burks
- The Flying Death (1928) B. Wallis
- Left by the Tide (1929) Edward E. Schiff
- The Net of Shamlegh (1930) Lieutenant Edgar Gardiner
- Ghouls of the Sea (1934) J. B. S. Fullilove
- Death in the Stratosphere (1937) Henry J. Kostkos
- The Monster from Nowhere (1939) Nelson S. Bond
- The Thing from the Barrens (1945) Jim Kjelgaard
- The Isle of Doom (1948) Robert Moore Williams