The girls try to protect Yan Lin, the last remaining former Guardian, from falling under Nerissa's control. Hay Lin and her grandma move from one dimension to another, trying to flee from the Knights of Destruction and Nerissa. Hay Lin has bad luck when her Fortune cookies haven't got fortunes in them.

Phobos convinces the Guardians to release Cedric and Miranda for more protection. Meanwhile, as it is Halloween, the one night in the year when a Heart can be taken by force, the Guardians have to protect Napoleon, as he is Lillian's familiar. The race is on to keep Napoleon away from Nerissa, but thankfully the girls are able to walk around in Guardian form because of the holiday. Phobos tricks Nerissa and assumes control over her Seal. Meanwhile, Irma is forced to take her brother Chris, Lillian, and Blunk trick-or-treating, only to discover that her crush Andrew Hornby likes to trick-or-treat too. Irma gives Chris and Lillian a crash-course in how to get the most candy, using her own powers to help.