Voyagers!

Phineas and Jeffrey help the Wright Brothers invent the airplane and Corporal Eddie Rickenbacker defeat the Red Baron.

Phineas duels Spartacus in a gladiator match in Italy in 73 B.C. then escapes to 19th century Hannibal, Missouri, where Harriet Tubman is fleeing for her life.

Jeff and Bogg arrive in the Cuban revolution, to find history changed because Teddy Roosevelt never led the charge up San Juan history. He was killed by Billy the Kid in 1889. The Voyagers head back to that time, stopping briefly to help Ben Franklin get his kite in the air. Once back in the Old West, the two infiltrate Billy's gang and then save Roosevelt's life. Billy turns out to be a coward without his gun, much to Jeff's dismay. Travelling back to Cuba to make sure history is on track, they meet up with Roosevelt and help the Cuban rebels, setting history right.

Bogg and Jeff land in colonial Massachusetts. Their arrival is witnessed by a local who has them arrested as witches. Benjamin Franklin's mother is also under accusation, and if she dies, history changes. Jeff uses the Omni to prevent him and Bogg from being burned at the stake, but that puts them a couple of centuries forward and right in the middle of a seance being attended by skeptic Harry Houdini. Witnessing the ""supernatural"" with his own eyes, Houdini starts believing in ghosts, further altering history. The Voyagers Omni out, but return when Jeff determines they must convince Houdini they aren't ghosts. He and Bogg end up saving Houdini from being rescued alive, and put that part of history back on track. They then return to Massachusetts with one of Houdini's mirror illusions. Using it, they show that there are no such thing as ghosts and witches: only mechanical trickery. That ends the witch trials, and history is restored.

The Voyagers are separated: Bogg is with Lawrence of Arabia, while Jeff is stranded in the 1800's with Thomas Alva Edison. When Jeffrey awakes after a rough landing, he learns that Edison has dismantled the Omni and not invented the light bulb. A piece of thread is the answer to the incandescent light but Edison can't figure out the Omni. He rebuilds the strange device and Jeff returns to Arabia, unknowingly saving Bogg and Lawrence as they are being led to their deaths. A chase through the catacombs leads Lawrence, Medina, and the Voyagers to safety and Lawrence is reunited with his people. The Voyagers return to Menlo Park to see the electric light used outdoors for the first time.

The Voyagers inadvertently bring Cleopatra forward in time to prohibition-era New York City, where she encounters gangster Lucky Luciano. In the main plot, Phineas has to convince young baseball player Babe Ruth to abandon his pitching career so that he will eventually become the home run hitter idolized by Jeffrey.