In a large guarded prison on a small island, the Annual Convention for
Police Chiefs and Wardens of America is taking place. Peter Parker, Bobby
Drake and Angelica Jones are also there, working. Angelica hopes they get
out of there on time, and Bobby asks if it's because she has a hot date. She
answers "maybe", and the boys start guessing who the date is with. As
Angelica and Bobby go to the kitchen, something turns on Peter's
spider-sense.

A performer goes on stage – a man called "Proton the Great", who claims he
can escape any prison. He easily breaks out of a cell and releases his
handcuffs. Peter thinks it's a great act, but wonders why it's turning his
spider-sense on. Then, he remembers – there's only one man who can pull a
stunt like that: Magneto, the most dangerous mutant of all.

"Proton" prepares for his next stunt – the escape from the Sands of Time. He
reveals to the audience a large sand-glass, and says he's going to enter and
turn it upside down, burying him alive. To prove this isn't a trick, Proton
asks for a volunteer. Peter, who already changed to his Spider-Man costume,
swings to the stage on his web, to the shock of everyone. Proton closes the
curtain on him and the wall-crawler, and Peter takes off Proton's hood – as
he figured, it's Magneto. The Master of Magnetism hurries to toss Spider-Man
into the sand-glass, turn it upside down, and open the curtain, this time in
his Magneto costume, revealing his true identity. He tells the amazed police
chiefs that he now places them under arrest, and creates a magnetic
force-field around the prison island.

The police chiefs want to take down Magneto, but Magneto takes all their
weapons and metals and piles them up on the stage, next to the imprisoned
Spider-Man. Now powerless, the chiefs are forced to listen as Magneto makes
his demands: each warden there has a mutant, a gifted associate of
Magneto's, in one of his prisons, shielded from Magneto's magnetic powers in
anti-magnetic cells. Those imprisoned mutants are the massive immovable
Blob, the obedient and super-agile Toad, and Mastermind, the master of
illusions. Magneto demands the release of his Brotherhood of Evil Mutants
within one hour, but the wardens refuse. Magneto realizes he'll have to
prove his powers, and sets a television screen to show a train station. He
then flies out of the prison and destroys empty trains in the station,
threatening to do it to more trains – he can starve entire cities, and he
will, if his Brotherhood of Evil Mutants won't receive total freedom.

Spider-Man is up to his shoulders in sand, and doesn't know what to do. He's
use his web fluid to stop up the sand, but the sand plugged up the web
shooters.

In the kitchen, Angelica and Bobby change to Firestar and Iceman. After
Bobby makes another wrong guess about who's Angelica's date with, the two
mutants get to the stage to help their friend. Firestar tries to melt the
glass, but the magnetic shield is causing sonic waves. Iceman's powers don't
work either. Firestar finds that the magnetic shield doesn't go under the
hour-glass, and heats up the bottom. Iceman follows by freezing it, and the
glass breaks. Spider-Man gets out and thanks his friends. He asks Angelica
about her date again, but she still refuses to say.

Not far away, in the Niagara Falls, Aunt May is on a ship with Ms. Lion,
watching a news report about the imprisoned police chiefs. She realizes that
the kids went there to work today, which means they must be held too.

After Spider-Man fixes his web-shooters, the three superheroes start
thinking of a plan. Just then, Magneto returns and attacks. Iceman tries
hail, but it's not effective. Spider-Man tries his web, but Magneto easily
frees himself from that too. Firestar next tries heat beams, but Magneto
counters it. Magneto repeats his demands, and flies off. Peter tells his
friends that he spotted something: when Magneto uses his powers, the
electricity goes down. Bobby concludes that Magneto is getting his extra
power from the Niagara Falls generators – if they’ll shut down those
generators, Magneto will lose most of his power. Peter suggests they'll draw
webs – the short web stays there to keep Magneto busy. Firestar burns her
web shorter and settles it – she'll stay. The boys leave to find a way out,
but not before promising to try and get her out in time for her date.

Magneto creates for himself a control room in a room in one of the prison's
towers with a control panel, and says he will wait for word of the release
of the mutants there. To make things move faster, he shuts down the
electricity in the northern-east coast and says he will only bring back the
power when his demands are met.

Firestar sends smoke to Magneto's control room through the air-conditioning
system, but Magneto sends back a negative magnetic blast to cool her off –
perhaps permanently. The room Firestar is in freezes, and her powers shut
down.

The ship Aunt May is in sails by the prison. Aunt May looks at it and wishes
the children hadn't insisted on working there to buy her a birthday present.
The captain tells her that this is as close as they can get with the
magnetic shield – no one can get in or out. Hearing that, Ms. Lion jumps out
of Aunt May's hands into the water. Aunt May calls her back, but the dog
just keeps swimming. The captain jumps after Ms. Lion to save her, but can't
find her. Ms. Lion goes underwater, and Aunt May thinks she's gone. The
truth is that Ms. Lion found an underwater pipe leading to inside the
prison. She swims in, gets out of the water, and starts looking for the
Spider-Friends.

Iceman ice-slides all through the bottom floors trying to find a way out
underneath the magnetic shield, but can't find anything. Suddenly, he hears
Ms. Lion – he looks, and sees her coming through an opening in the floor. He
realizes he can get out the way she got in, and she runs off to find
Angelica.

In his control room, Magneto sees Iceman escaping with a security monitor.
He then goes to dispose of the web-slinger.

Spider-Man has put on a spacesuit, and is climbing a wall. He gets to the
top and tries to make a leap, but the clumsy costume makes him fall. Magneto
uses his magnetic powers to trap Peter in a large metal container and shut
it close. Peter tries using his super-strength to escape, but it doesn't
work. Magneto then lifts the container and takes it to the Niagara Falls.

Ms. Lion gets to the door of Angelica's frozen room, and Angelica thinks
she's dreaming when she hears her dog. Angelica concentrates with all the
heat she has left and blows up a gas pipe, steaming up the room again. With
restored powers, she blows up the door and leaves. Ms. Lion hurries to lead
Angelica down to the exit.

Magneto drops the container with Spider-Man into the water, and it's close
to falling down the Niagara Falls. He then uses iron filling to make the
falls go upwards instead of down, and the container gets on top of the
water. He plans to cut off his power, making Spider-Man fall to the rocks
below. Just then, Iceman arrives on an ice-slide. Peter manages to open the
container, and finds he is high in the air. Magneto then releases his power
and leaves, and the container drops. Bobby hurries to freeze the falls, and
the container gets stuck in the ice. Spider-Man gets out through the
opening, and the two superheroes leave to the power plant.

Magneto returns to the prison and says he lost his patience, demanding the
immediate release of his mutants, or else he will lunch every nuclear
missile in the country. Helpless, the policemen decide to do as Magneto
says.

The door to the Blob's cell opens, and the unmovable mutant leaves. Toad's
cell opens as well, and he hops out. Mastermind too leaves his cell. The
guards at his jail say that with an army of evil mutants to obey him, no one
will ever stop Magneto.

Ms. Lion leads Firestar all the way to the pipe she came from, and Firestar
realizes that the way out is under the magnetic shield. She can't leave yet
though, because her work is not quite finished there – the power goes off
and on, indicating magneto is using his power. She flies back up to the
stage and attacks Magneto with heat beams. Magneto reacts by tying up
Firestar with wires, and she falls. He laughs victoriously, and Firestar
tells him he won't be laughing when Spider-Man and Iceman will shut down the
Niagara Falls Power Plant. The Master of Magnetism realizes that he can
waste no more time with Firestar, and flies off to stop her friends. One of
the wardens accuses Firestar of betraying her friends to Magneto, but she
tells him not to believe everything he hears. She then burns down the wires
and flies away.

In the power plant, Peter tells Bobby that they got to get Magneto between
the two big generators. Bobby sarcastically asks if they're gonna send
Magneto an invitation, and Peter answers yes – and it was already delivered.
As if to confirm his words, metal objects start flying around the room, and
the superheroes hurry to take cover. Iceman encases himself in ice, and
Spider-Man leaps out of the way. Magneto enters and, before he can react,
Spider-Man ties him in web and Iceman freezes his legs in a square block of
ice. Peter then pulls the web, and Magneto slides on the ice straight to
between the generators. Bobby activates them, and the generators start
charging Magneto.

Meanwhile, Firestar flies to the frozen Niagara Falls and shoots fire at
them, defrosting them.

Magneto calls Spider-Man and Iceman fools – they're not decreasing his
magnetic attraction, they're increasing it. What he doesn't know is that
that exactly was Peter's plan – now, he's too powerful, and has no control.
All the metal objects in the plant start flying towards Magneto, and Magneto
hurries to fly out. The metal follows him up and traps him in the air, and
the magnetic shield around the prison is removed. The police chiefs cheer,
and the Brotherhood of Evil Mutants is trapped again before they can leave
their jail.

The Spider-Friends gets to Magneto and find him unconscious – this case is
wrapped. The boys keep guessing who Angelica's date is, but she just tells
them that of all the men she ever met, Magneto is by far the most
attractive.