Heavily pregnant Lenore Davis tells her husband, Frank, that she is in labor. They leave their eleven year-old son Chris with their friend Charley and they head to the Community Hospital. Lenore feels that something is wrong and delivers a monster that kills the team in the delivery room and escapes through a skylight. Lieutenant Perkins comes to the hospital to investigate the murder and the press divulges the identity of the parents. Frank discovers a dark secret about Lenore and the baby.

Meek and mild mannered bookkeeper Henry Limpet has few passions in life. It's mid-1941 and he would love to join the Navy but has been rated 4F. His friend George Stickle is in the Navy and lays it on pretty thick. If Henry could have one thing it would be to become a fish. While on a visit to Coney Island, Henry falls into the water and miraculously gets his wish. Now a fish, he makes friends, Ladyfish and Crabby the hermit crab and loves his new life. He also uses his abilities to help the US Navy locate and sink Nazi U-Boats, forcing the Germans to create a new weapon to deal with the Allies secret weapon. When years later the Navy finds intelligent activity among dolphins, they may also know who is teaching them.

Super-spy Flint takes on a cabal of women plotting to rule the world.