Helping someone who's been targeted

This is the hardest page here, because the instinctive response — disbelief, then frustration that they didn't see it — is precisely the response that keeps people from telling anyone, and silence is what allows the loss to keep growing.

The first hour, if money has moved

Call the bank immediately. Speed matters more than anything else. Some transfers can be recalled if the bank is told quickly, and that window is measured in hours. Do this before working out what happened, before talking it through, before anything.
Stop any payment still in progress and don't let anyone send a further penny — including any fee that supposedly releases the earlier money.
Change the password on their email first, then anything financial. Email is the master key to everything else.
Keep everything. Messages, numbers, account details, screenshots, the platform's name. Don't delete it in anger or embarrassment; it's what any investigation runs on.
Report it. Local police, and the FTC at reportfraud.ftc.gov or the FBI at ic3.gov. Reports rarely recover money, but they're how patterns get spotted and how these operations are eventually reached.

Before you say anything else

"How could you fall for that?" is the most natural sentence in the world here, and it does more damage than the scam's next message. Shame is the mechanism that keeps people quiet, and quiet is what the whole thing depends on. Try instead: this was designed by people who do it full time, and it was designed to work.

When they don't believe you

The hardest version is a scheme still in progress, where the person is still in contact and doesn't accept that anything is wrong. Frontal argument almost always fails, because they've usually been prepared for it — told that family will be jealous, or won't understand, or will try to interfere.

What tends to work better:

Ask questions rather than issuing verdicts. "What happens if you try to withdraw it now?" invites them to test the thing themselves. Being told they're being conned invites them to defend a decision.
Aim at the mechanism, not the person. "Nobody real ever requires a fee before releasing your own money" is a fact about the world. "You're being scammed" is a judgement about them, and gets argued with.
Stay in contact even while disagreeing. An ultimatum that ends the conversation hands them entirely to the other side. Being the person still willing to talk is worth more than being the person who was right.
Bring in a third voice. A bank's fraud team, another relative, a friend their own age. Sometimes the same words land differently from someone who isn't family.
Give it a little time. Doubt usually arrives on its own, and what matters most is that when it does, they know exactly who they can call without being humiliated.

After the money is gone

Two things follow that are worth being ready for. The first is a second approach — a recovery service that has heard about their loss and can get it back for a fee. This is frequently the same operation returning for what's left, and it works because desperation is easy to sell to. Nobody who can genuinely recover funds finds you first and asks for money up front.

The second is the emotional weight, which is usually worse than the financial one and lasts much longer. People describe it as feeling stupid, and it commonly comes with real depression, particularly for someone who was targeted through affection over months. Losing money is one injury; losing confidence in your own judgement is a deeper one. If that's where someone is, treat it as seriously as the money, and don't leave them alone with it.

Say this out loud at some point

Being deceived by a system built by professionals, tested on thousands of people, and tuned specifically to bypass judgement is not a failure of intelligence. Careful, capable, sceptical people are caught by these every day. The person who tells someone quickly, before the second and third payments, has done the single most useful thing available — and that only happens where telling someone feels safe.

If you'd rather prepare than react

Nearly everything above becomes unnecessary if a family agrees on two habits in advance: a code word for urgent calls, and a standing understanding that any request for money gets checked with one other person first, with nobody ever thought foolish for checking. Neither requires technology. Both are worth more than any tool on this site.