Plankton and Karen the Computer, played by Luke Hierholzer and Elise Muether, laugh villainously as their evil plan starts to work during a dress rehearsal for Celina High School's "Spongebob the Musical" on Tuesday evening. Performances are at 7:30 p.m. April 4 and 5, 3 p.m. April 6, 7:30 p.m. April 11 and 12 and 3 p.m. April 13 at the Celina Education Complex. Tickets, available on hometownticketing.com or at the door, are $9.