Great authors know how to keep on surprising their readers, even from beyond the grave.

Agatha Christie had her share of surprising and mysterious adventures while alive. And though she died in 1976 at age 85, she recently provided one more, thanks to a mysterious lockbox.

According to the Los Angeles Times, Christie fan Jennifer Grant purchased a trunk that once belonged to the famed author and discovered a lockbox bolted inside. Given the source of this mysterious box, Grant said she "almost did not want to open it because then the mystery would be over."

After four years, however, the temptation proved too great and she pried the box open. The box did not hold an unpublished manuscript for a Hercule Poirot or Miss Marple novel, but Grant did find gold coins, as well as a three-stone diamond ring and a diamond brooch.

The jewels, mentioned in Christie's autobiography, were sold at auction this month. According to the Times, the brooch and ring were expected to bring in $15,000 to $20,000. Instead, they sold for a combined total of more than $80,000.

Not a bad return on investment, considering Grant originally purchased the trunk, with the jewels, for $160.