The team arrive back on earth safely, after the second Stargate is
brought on line. But O'Neill and Teal'c must fight the surviving
replicator, which has taken over a Russian submarine. And Carter goes
with a desperate Thor to try to come up with a "stupid" idea
that might save his world from a final replicator attack.
4.02.
The Other Side
Earth receives a desperate plea for help from a race losing a
dreadful war. SG-1 goes through the Stargate to help. They contact
people who agree to trade advanced science for heavy water. But all is
not as it seems. The people are eugenicists trying to exterminate their
foes, the Breeders, by poisoning the planet. Earth refuses to help --
and O'Neill helps the other side destroy the poison gas base.
4.03.
Upgrades
A Tok'Ra arrives with three armbands that might be able to give the
wearer superhuman powers. O'Neill, Carter and Daniel volunteer to try
them out. They get stronger, smarter and faster, but there are
side-effects. They also get reckless, and have metabolic problems. But
they discover they can't take the armbands off. Then news comes through
that Apophis is building a super battleship. The three dash off to
destroy it, but then they "reject" the armbands, and are left,
unenhanced, inside the enemy compound. Fortunately, Teal'c is there to
help.
4.04.
Crossroads
An old flame of Teal'c's believes she had communicated with her
larva, and turned it from the Dark Side. She goes to the Tok'Ra, where
the larva is given a willing host -- but it was lying, and is still
evil. It kills Teal'c's love, but the Tok'Ra allow it to live, so they
can feed it false information.
4.05.
Divide and Conquer
A member of SGC tries to kill the leader of the Tok'Ra, under the
influence of a Goa'uld mind-control device. Another member goes berserk
when tested for the control. Then Carter and O'Neill both fail the test.
But that was because they had failed to say precisely why O'Neill had
stayed with the trapped Carter
[
4.03.
Upgrades
]
when trying to destroy Apophis' new ship.
4.06.
Window of Opportunity
The world gets caught in a 10-hour long time loop, and only O'Neill
and Teal'c are aware of it, in a
Groundhog Day
scenario
4.07.
Watergate
The second Stargate wasn't destroyed on Thor's ship's re-entry, but
was found by the Russians. Now it is stuck open, and the Russian
scientist in charge calls in SG-1 for help. They close the gate, but
Carter and Daniel are trapped under water, while O'Neill and Teal'c try
to discover what happened to the kill all the base personnel. They
discover the fault lies with the water.
4.08.
The First Ones
On the planet where the Goa'uld may have evolved, Daniel gets
captured by a descendent of the first Host species, the Unas, and the
rest of the team have to rescue him, dodging proto-Goa'uld as they go.
4.09.
Scorched Earth
SG-1 have relocated a population to a welcoming planet -- but then a
terraforming ship starts to destroy it. It looks as if one or the other
civilisation is doomed to perish.
4.10.
Beneath the Surface
SG-1 are missing on an ice-age planet, reported dead by their hosts.
Actually they have been impressed with new memories, and are working in
a slave labour camp. Their own memories start to break through, giving
them a chance of escape, but at the same time posing a threat to their
captors.
4.11.
Point of No Return
Someone contacts O'Neill, claiming to be an alien. He seems like a
harmless nut-case. But when SG-1 investigate, strange things start to
happen.
4.12.
Tangent
O'Neill and Teal'c test-fly a new fighter craft built using Gou'ld
technology. But it is booby-trapped, and whisks them off past Jupiter,
with their life support running out. Carter and Daniel plan a desperate
rescue.
4.13.
The Curse
Daniel's archaeology professor is killed in a lab accident. The team
find a Goa'uld larva in stasis in an ancient jar, and another opened
jar. A new powerful Goa'uld has taken over an ex-girlfriend of Daniel's,
and eventually escapes from earth.
4.14.
Serpent's Venom
Teal'c is captured during an undercover mission. The rest of the team
are helping Carter's father in a plot against Apophis, trying to trick
him into a war with another powerful Goa'uld. They discover Teal'c has
been captured, but should they give up their mission to save him? They
don't, and the mission succeeds, and Teal'c is saved by a Tok'Ra. Then
they discover their mission has actually made Apophis more powerful than
ever...
4.15.
Chain Reaction
General Hammond retires, and the team discover NID was trying to
blackmail him to do more weapons reasearch. O'Neill gets enough
information on a senior NID member to counter-blackmail.
4.16.
2010
10 years after SG-1 discovered a friendly alien race who helped them
defeat the Goa'uld, Sam discovers they aren't that friendly after all.
The race is on to send a message back in time, using the solar flare
method
[
2.21.
1969
]
that previously sent them back in time.
4.17.
Absolute Power
The child of Apophis and Daniel's wife
[
3.10.
Forever in a Day
]
reappears from where he had been
hidden
[
3.20.
Maternal Instinct
]
,
apparently now about 10 years old, with his Goa'uld racial memories
deliberately forgotten. Daniel tries to convince the wise child to
release the memories, and the child teaches Daniel why this cannot be.
4.18.
The Light
The team get addicted to a strange light on an alien world, suffering
potentially fatal withdrawl symptoms. They have to work out how to beat
it, else they will be forced to stay on the world for the rest of their
lives.
4.19.
Prodigy
Carter has problems with a brilliant but sullen cadet.
4.20.
Entity
A computer program invades SGC. Despite their attempts to wipe it, it
manages to build itself a system, and starts communicating. When Carter
tries to communicate it infects her, and refuses to leave. It tells them
they caused great damage with their probe. Daniel wants to reassure it,
but O'Neill threatens to send more probes unless it leaves Carter. It
starts a download, and O'Neill is forced to kill Carter. But the
download was Carter's personality, and only the entity is killed. The
doctor rigs up a connection between the alien system and Carter's body,
restoring her.
4.21.
Double Jeopardy
The android SG-1 team
[
1.19.
Tin Man
]
arrive at a planet, and are captured by
the locals, who were previously visited by the real SG-1, who liberated
them from the Goa'uld. But the planet has subsequently been taken over
by a new Goa'uld, who arrived by spaceship. The real team find out
what's happening, and feel responsibility for the planet's inhabitants,
so go to kill the new Goa'uld and liberate them again. All the androids
die, heroically, in the ensuing battle.
4.22.
Exodus
Earth has loaned the captured Goa'uld spaceship to the Tok'Ra, who
are going to use it to take their Stargate to a world off the Goa'uld
maps, and so be safe. The Goa'uld pretending to be a Tok'Ra
[
4.04.
Crossroads
]
realises it has been discovered, escapes, and warns Apophis. So Carter
plans to open the Stargate onto the black hole planet
[
2.15.
A Matter of Time
]
, then throw it into the local
sun, causing it to go supernova and destroy Apophis' fleet. But things
go wrong, Teal'c is captured by Apophis, and the rest of the team are
blown far into another galaxy, along with Apophis' ship...