A lady might contact you by e-mail saying that her husband died and all his savings are in a trunk box, deposited at a security company outside their country (usually an African one, such as Nigeria, Ghana or Ivory Coast).
You are asked for help in recovering the box, with a promise that you will be paid 20% of the contents, which apparently are millions of dollars. She will send you the deposit certificate and she will make you the beneficiary of the box, if only you can help her. You and she talk on the phone and she gives you the name of an attorney, who knew her husband and will help you in the process.
The scam starts when the lawyer begins asking you for any kind of fees, which will lead to you losing money and never getting anything back.
How to avoid: never get involved in deals that involve getting money out of Africa.