Guardian Angel was first published in the April 1950 issue of Famous Fantastic Mysteries. It was later expanded to become the first part of the classic novel, Childhood's End. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"Critical Mass" was first published in the August 1957 issue of Space Science Fiction Magazine. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"A Walk in the Dark" was first published in the August 1950 issue of Thrilling Wonder Stories. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"Neutron Tide" was first published in the May 1970 issue of Galaxy. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"Nightfall" was first published in 1947 in King's College Review. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.