The basis of the plot is that humanoid aliens arrive on Earth. They are friendly and seek the help of the inhabitants. They are, naturally, concealing the deadly truth of their visit and their nature and only a few humans recognise the threat and act against them.
The story is an allegory about the rise of Nazism. There are very clear references to the Holocaust, the dangers of appeasement and the rise of organised resistance in occupied countries. The story was apparently inspired by the 1935 novel by Sinclair Lewis It Can't Happen Here.
The series ran for 200 minutes and was successful enough to spawn a sequel, V: The Final Battle and a television series in 1984-85. Johnson left V during the sequel but went on to work on other science fiction shows such as Alien Nation.