The narrative revolves around the efforts of a mediocre film director to save his job, his livelihood and just incidentally the studio he works for. To do this, he enlists a mad scientist, the crooked studio owner, a cowboy, two fabulously stupid movie stars, and a real live ocean-crossing Viking He ends up making history, but in a way he never dreamed of.
Barney Hendrickson is a mediocre movie-maker with no prospects, and his employer, Climactic Studios, is about to go out of business, particularly as the owner, L M Greenspan has systematically looted the corporation. In desperation, he drags Greenspan to see Professor Hewitt, who claims to have a time machine. Hewitt's idea of a demonstration is not Greenspan's, sending a bottle half a second into the past. Barney desperately takes over the machine, turns everything up to maximum and sends Greenspan's Cuban cigar three seconds into the future, burning out the circuitry in the process.
"L M" is convinced enough to finance a replacement, under cover of a mad scientist's plot device for a horror movie. Barney aims to make a historical movie in the past, with a minimal crew, a handful of actors, and all the other parts filled by extras recruited (hopefully for wampum and beads) from the local people. His first script isViking Columbus, about the founding of the Vinland settlement, obtained by sending Chinese-American scriptwriter Charley Chang back to a barren Precambrian for a month.
On the first trip, they capture a Viking named Ottar in Orkney of the 11th century. With Ottar as local guide and interpreter, paid in bottles of Jack Daniel's, they move an entire sound stage into the past and begin filming. Their stars are Ruf Hawk, a narcissistic he-man, and Slithey Tove, a sex goddess.
In the present the auditors from the bank are arriving in a few days, at which point they will discover the cooked books. Also, Prof. Hewitt explains that the time machine must return to the present, a moment after departing, before going to any other time. As a consequence, time used in the present day is lost forever. Barney thinks he can stay in the past as long as necessary, but following an attack by marauders shortly after their arrival, Ruf is injured and refuses to participate in the film. Then the time machine itself breaks down in the present day, taking hours to repair.
Improvising desperately, Barney casts Ottar in the lead and resolves to stay in the past until all is done. They film Ottar setting sail for Vinland with an actual colonising crew, then the movie people jump, via present day Hollywood, to Newfoundland a few months later, tracking Ottar by a radio beacon on his boat. While waiting, they have a nasty encounter with the natives, whom the Vikings will call skraelings
Ottar hits the beach and digs in while the cameras roll, then the crew jumps forward a year to give the colonists time to build the settlement and stockade. They learn that Slithey, who had become smitten with Ottar, had been left behind by accident. Not only that, she has Ottar's baby son on her hip.
They continue filming, even during a mass attack by skraelings, which is repelled with tear gas and Viking axes. Shooting the final scenes, Barney is triumphant - and downcast. Even with all the film shot, he still has to do a soundtrack, dub the spoken lines, and edit the final cut. There is no time in the future to do this, and no equipment in the past. All seems lost.
Barney is all set to walk into Greenspan's office empty-handed, when he is stopped by a surprise visitor - a future version of himself, carrying a finished copy of Viking Columbus and sporting a bandaged left hand. He reassures Barney #1 that all he has to do is return to the past and complete Viking Columbus, and that everything will work out in the end. Barney #2 then walks into Greenspan's office with the completed film, leaving Barney #1 to wonder about what happened to his hand.
Filled with confidence, Barney #1 heeds his counterpart's advice and returns to Vinland to finish the film. Along the way, however, he gets a wood sliver in his hand
With the movie a smash hit, Climactic's future is assured. Only one puzzle remains. The Vikings went to Vinland, but where did the real settlers land? The Norse sagas say that the expedition was led by Thorfinn Karlsefni but there was no sign of him. Then Ottar, overhearing, reveals that his formal name is indeed Thorfinn Karlsefni. Shocked, Barney and Hewitt realize that the colony was founded because they decided to make a movie about founding the colony. Not only that, but Slithey, whose character in the movie was named "Gudrid", has also entered history as the mother of her son, whom she called "Snorey" because he snored so much. He will be known as Snorri Thorfinnsson the ancestor of many Icelanders.
The sagas also mention another important figure, Bjarni Herjólfsson Barney Hendrickson realizes: "They wrote a part for me!"
The novel ends with Greenspan planning to produce a historical film about the crucifixion of JC shot on location in 1st Century
This novel presents a clear use of the restricted action resolutioN of the Grandfather paradox. The actions of the characters can not have changed the past because the past is what their actions brought about. For example, you couldn't go back in time and kill your Grandfather because then you wouldn't be born.
A curious fact which probably escapes most English readers: The company's linguist's name, "Dr. Jens Lyn", is actually the Danish name of comic book character Flash Gordon - a homage, probably, to Harrisons many Danish friends - he lived in the country for a while. References of that kind can be found in several of his books, i.e. the placename "Storhestelortby" in "Bill the galactic hero" means "City of big horse shit".