Selena Drake was an evil scientist working as the Executive Chief at Shermantech headquarters, underneath Travis Sherman.
After a discovery of the Spooker 3000, thanks to Shaggy and Scooby, it is revealed that Selena was behind the plot to release ghosts and monsters from the Tome of Doom. The "S.D." in the telegram for Walter Peabody turned out to mean Selena Drake. Walter passed the missing pages of the book to Zabrinski, who then passed some to Mindi, who all used them to summon ghosts and demons. The mind-controllers ruling Fred, Daphne and Velma are shut off. Then, Alan Dinsdale appears. Alan explained Selena also planned to rule the world with the use of mind-controlling antennas, founded by Sherman Tech. With the confusion, Selena escapes, releasing one of the final monsters, The Fire Ghost. When arriving in the Courtyard, she released the ultimate monster, The Fire King. After Shaggy and Scooby beat him, Selena is put in jail after Mystery Inc. defeated her and her evil released monsters.