Doug and Tony land 10 years in the future on the Mars Excursion Module during liftoff. Their extra 335 pounds of weight endanger the mission by putting it over the weight allowance. Everyone believes the time travellers are spies except one man, Harlow. They are forced to land on the moon for a refueling stop, but the ship crashes. One of the other men, Beard, kills Harlow. Beard is a spy. To further confuse matters, ten years in the past at Project TicToc, Beard and another spy, Brandon, are visiting the complex. Brandon sabotages the tunnel and then tries to escape, but Beard shoots his superior to bolster his own cover and his own role remains undiscovered. In the future, Doug and Tony manage to blow up the ""future"" Beard, but the MEM takes off without them. As they are stranded on the moon, their air running out, the Tunnel scoops them up and sends them on their way. (Copyright 2003 Steve Crow)

Tony and Doug land in the War of 1812 in Louisiana, and steal som clothing that happens to have passes from General Jackson. They are captured by the British forces, led by Colonel Southall. In the present, the Project people bring in Southalll's descendent, a British general. His ancestor has a reputation as a butcher by sending his men into the strongest flank of the American forces. In the past, Col. Southall forces Tony to lead one of his men to the enemy lines, get a report, and send up a signal rocket of which flank he should attack. Tony and the scout get captured, escape, and prepare to send the signal. Meanwhile, General Southall insists on returning to the past. He's dying of cancer, and Kirk reluctantly grants the general, an old friend, his last request. The present Southall helps Doug escape and then confronts his ancestor and manages to convince him he is from the future. Doug helps Tony but the signal rocket goes astray and the attacking British are wiped out. General So

The guys arrive in South Dakota in June 24, 1876, near Little Bighorn. They are captured by Indians, although Doug manages to escape and make it to Custer's camp. Custer refuses to believe Doug's tale. Meanwhile, Tony has tried to warn Sitting Bull. The Indians prepare to burn Tony at the stake, but Sitting Bull intervenes, impressed by Tony's bravery. A trial-by-combat settles the matter when Tony wins against Yellow Elk but spares his life. Tony tries to convince Sitting Bull to approach Custer peacefully, much to the disgruntlement and skepticism of Crazy Horse. Sitting Bull lets Tony go to Custer's camp with a message of peace, but Custer refuses it and locks both travellers up. They manage to escape, and are forced to watch as history plays itself out and Custer and his men are massacred.

The guys arrive in Paris, 1793, and Doug is arrested by the Committee for Public Safety. Tony rescues him with the aid of a shopkeeper, who is a royalist and friend of Marie Antoinette. Meanwhile, Kirk has the Project send back an irradiated personal ring to the guys which they hope will act as a focal point to home in on. Doug and Tony get the ring, but then reveal themselves to a man who is a splitting image of General Kirk! This General, Querque, is with the Revolution and has them arrested, along with the shopkeeper. Querque has the ring and believes it is the evidence he needs to have Antoinette executed. Kirk brings his ancestor into the present and tries to convince him to change his mind. Querque escapes back into the Tunnel when they send the ring back, and tries to thwart Doug and Tony. They escape, and with forged passports get to Marie Antoinette and then help the Dauphin to escape. The shopkeeper and the Dauphin get on board a departing ship: Tony recognizes the Corsican g

Tony is shot by Afghani tribesmen and left for dead, and they then take Doug prisoner. Doug is taken before Singh, the head of the Afghanis fighting against the British in 1876, while Rudyard Kipling rescues Tony and takes him to the English fort. The Afghanis are preparing for a massive attack on the English, the 'Night of the Long Knives'. With the aid of a blind slave, Doug escapes and gets back to the fort, while Kipling is captured. The general in charge has been ordered to only defend himself, so he has the head of the Afghani forces under English command launch an ""unofficial"" attack. Doug and Tony accompany them and rescue Kipling, and Singh is killed in the attack.

The guys land in a Western town in the late 19th century, where they are intercepted by two silver-clad aliens. The two aliens need to steal protein to supplement their own supplies, and soon use their advanced technology to mind-control Doug and hold the confused townspeople at bay while stealing local cattle. Tony manages to get hold of one of the alien control devices. Meanwhile, at Project TickTock the same alien race but from 1966 arrive and demand to know what happened to their scouting party a hundred years earlier, believing the Project to have something to do with it. Tony manages to free Doug from mind control and defeat the aliens in the past, while the ones in the present witness the departure of the scouting party in the past and are satisfied Earth had nothing to do with their disappearance.

Tony and Doug arrive outside the tent of Joshua on the sixth day of his seven-day assault on Jericho. With their future knowledge of the Bible they are able to convince Joshua that they are emissaries of the Lord, and he basically forces them to go into Jericho as spies. Doug is captured and tortured after they try to stop an exection, and Tony befriends a harlot, Rahab. With the help of Rahab and her father, a blind architect, they manage to free Doug. Tony and Rahab are set up for execution, but when a skeptical Anne tries to use the Tunnel to free them in opposition to how the Bible describes the incident, the Tunnel shuts down as if by some outside (dare we say Divine?) force. Tony and Rahab are spared when Joshua launches his attack and both the guys and the Project team witness the miracle just before they are whisked away once more.

The guys arrive in Arizona, 1547, as a technician named Niman kills a scientist. After a shootout, he flees into the Tunnel. Niman is a spy who has planted a nuclear device in the complex. The guys need to find Niman to get him to reveal the location of the bomb. They lure him in with a fire but he slips, and the Project transfer Doug and Tony after him to 1,000,000 A.D. Niman is already there and has established himself with the ruling clique. The guys get the info on the detonation time, bypass a force field, and with the aid of a local female ""defective"" manage to get to Niman. The Project transfers everyone, including two of the future-types, back to 1,000,000 B.C. After some running around from dinosaurs, they rescue Niman from a quicksand pit in return for the location of the bomb. The head alien eventually comes around and forces Niman to give the location of the bomb which they defuse. Everyone ends up in a giant bee hive and the Project gets everyone but Niman out.

Tony and Doug are frozen in time, then a rather fey Merlin appears in the Project base. He takes the guys out of time and freezes them, commands them to do his bidding, then sends them on to 544 A.D., Cornwall England. They meet a young pre-King Arthur while fighting Vikings and on Merlin's behest team up with Arthur. The Vikings apparently kill Doug and capture Tony and Arthur. Tony escapes with Arthur and Doug is rescued by Merlin and Guienvere. When the Project staff are ready to recover Doug and Tony, Merlin intervenes because he needs them where they are. Tony and Arthur get recaptured and so does Doug when he goes to help. Guinevere gets captured too. One of the Vikings kills Arthur and a ""detained"" Merlin shows up and reverses time to save him. The guys escape again and Doug gets reinforcements which Merlin disguises as Vikings while Arthur and Tony rescue Guinevere. Everything works out and Arthur and Guinevere are to be married.

The guys arrive in a brick basement on the North Atlantic coast in 1978. It has advanced electrical equipment, and they are attacked by an overalled man. He collapses dead, then gets up and disappears in a cloud of smoke. They go upstairs and are paralyzed by an alien-android disguised as an old woman. The aliens are preparing to steal Earth's oxygen. The Project staff execute a lateral transfer and free the guys. They escape to a seemingly empty town surrounded by a force field and filled with paralyzed townspeople. A young couple, Paul and Joan, find the guys and tell them about the oxygen-stealing plot. Meanwhile the alien androids infiltrate the Project base, seal it off, and start sucking out the oxygen through the Tunnel itself. The guys must destroy the operation at their end. They fight off the androids and use explosives to blow up the alien HQ.