Entertainment Weekly reports that the actress, who currently stars in ABC's V, will play a character named Erica Flynn.
The owner of a matchmaking business, Flynn will be forced to hide some dark secrets when she crosses paths with Jane (Simon Baker).
More at the link.
The Mentalist airs Thursdays, CBS, 10 PM ET. Morena's episode is supposed to air sometime in early April, but right now, the exact episode/date hasn't been announced.