A suspicious baby-sitter . . . a pair of conspiracy theorists . . . more secret codes from Spy X. Twins Evie and Andrew have more than a mystery on their hands.

Evie and Andrew have always wondered what happened to their mother after she disappeared on their birthday. Now they are starting to find out . . . and the results are very surprising. Their mother was into something big, and now the twins are being drawn in as well. Nobody - not their baby-sitter, not their new school friend, not a pair of menacing bikers - is who he or she appears to be. But Evie and Andrew will have to uncover the truth if they ever want to see their mother again.