The alien race that Steve fought before (in "The Secret of Bigfoot") need supplies of metal and jewels and send their Bigfoot android to steal them from U.S. government depots. Seeing the results of the unseen android's efforts, the authorities conclude Steve is responsible and arrest him. To clear his name, Steve must escape and track down the aliens.

In her efforts to save Steve's life, Jamie is confronted by Bigfoot.

Steve is present at the test flight of his friend Kelly Wood when she is shot down by a World War II Japanese Zero! Later Kelly is found but the plane has vanished and she's suspected of selling it to a foreign concern. Steve must clear her name and discovers a sinister plot to steal top-secret aircraft.

Billy Parker, a comedian, who resembles an African leader is implanted with a device that controls his actions. After being struck by a car he is brought to the hospital and after being X-rayed, the device is discovered. Steve is assigned to find out why he was implanted.

Steve and Rudy go to check up on a scientist, Cheryl Osborne, who was doing research on chimpanzees but who has ceased communications. When they arrive they find something has destroyed the lab, and Rudy is bitten by a rampaging chimpanzee. Rudy begins to turn into a psychotic and Steve must both stop him and find Osborne before it's too late.

Steve must infiltrate the deadly Omega spy ring as an underwater diving expert to thwart their theft of a device capable of separating the hydrogen and oxygen in water.

Jaime lies near death after being attacked by two Fembots. Meanwhile, Steve locates the compound where Oscar is being held and attempts to rescue him.

Athlete Andy Sheffield is badly injured in a landslide, the accident also killing his controversial father. The heads of the O.S.I. decide to sanction the use of Doctor Rudy Wells’ bionics in order to restore life to Andy’s paralysed legs, and the athlete soon begins a full recovery.

Andy sets out to clear his father's name and find the people responsible and Steve has to help him out.

Steve must stop a terrorist trying to blackmail the government.

To save the life of a young middle-eastern prince from rival factions, Steve goes undercover as a Thunderbird pilot and must smuggle him out of the country.

To save the life of a young middle-eastern prince from rival factions, Steve goes undercover as a Thunderbird pilot and must smuggle him out of the country.

other characters: Sissy Crandall (Bob's other daughter) When Steve is sent to investigate problems with an OSI project contracted out to Budge Corp., he discovers the problem is that the corporation's owner, Horton Budge, is a cheap ""Scrooge"". Steve then uses the same strategy from the Charles Dickens classic.

other characters: Jim (helicopter pilot) Steve goes undercover as Steve Ferguson, a hired mercinary, in order to infiltrate a ring of thieves attempting to steal a military missile called the Hornet.

Steve's friend Joe Patton is the subject of a unique experiment to transfer information directly from a computer to a human brain. Patton becomes the OSI's newest super-agent but the process has hidden dangers...

The Soviets have created an experimental Venus probe out of a new alloy, but it crashes in Wyoming. Thinking it's on Venus, the probe prepares to destroy a small town. The Russians send a team of agents in to recover it, while the OSI is desperate to stop it before it kills. Complications arise when it becomes clear the probe is stronger then Steve.

With time running out as the probe approaches the Wyoming town with the intent to destroy it, Steve must outsmart the probe when both the armed forces and his bionics prove useless against it.

Danny, a 14 year old kid, inadvertently creates a source of chemical thermal energy source while trying to create a new fuel source for his toy rocket. When his chemicals are stolen from his garage laboratory, Steve and OSI must protect Danny and catch the thief before he sells it on the black market.

A crooked trio manipulate a conservation group into halting an oil drill so they can get at the uranium underneath, and Steve is sent in disguised as a oil worker to find out what's up.

Steve poses as an amateur boxer to get the goods on an infiltration ring targeting expatriate athletes.

Steve trails a East German scientist who fakes a heart attack at a conference, then goes to a traveling carnival located suspiciously close to the test flight of a new B-1 bomber.

An ex-submariner from the English Navy raises an abandoned Nazi U-boat and threatens to use its deadly cargo against the U.S. unless they give in to his extortion demands.

Steve is sent to impersonate an eccentric scientist who is recruited by the Russians. He discovers they are working on a project involving a mind-reading computer, but time is running out on how long he can maintain the impersonation.

A crooked Indian medicine man kidnaps two OSI scientists to protect his plan to sell radioactive ore, and Steve is sent to recover them.

Steve is framed for espionage when the writing on research papers for a special formula disappear before his very eyes. Seeking to prove himself, he runs afoul of a pair of twins seeking a cure for their rapid-aging disease, and the formula can provide them with what they need.