Magneto has figured out that the X-Men must be based in the New York City area, so he has a mission for the Brotherhood.
What a team. Meanwhile, from his sub, Magneto launches his own attack on New York.
That was one of the most fun parts of the shared Marvel Universe in the old days. With everyone based in New York, anyone could show up in the book. This was frustrating for the villains. They'd be looking for revenge against their usual heroic foe, only to get someone else.
Thor is able to track the waves to their source.
This being when not being in contact with the hammer for a period turned Thor back into Don Blake (which Magneto doesn't see), the Master of Magnetism gets a little time to recover and check on the Brotherhood. The X-Men have turned up, and are kicking the Brotherhood's asses. Meanwhile, Dr. Blake has recovered the hammer.
Magneto uses his usual method to escape, leaving a bomb that will destroy a city that the hero must take care of. Very soon after this, two of the Brotherhood will quit and join Thor's team, the Avengers. The public will be concerned about these former members of the Brotherhood of Evil Mutants, but will be reassured when those trusted heroes, the X-Men, vouch for Wanda and Pietro.
No, really, that's what happened. The X-Men used to be viewed as heroes just like the FF and Avengers, only born with their powers.
That's why I find it annoying when Marvel portrays, in stories set in the old days, the public's hostile attitude towards the X-Men as how it has always been. Um, Marvel, some of us have read the old comics.