Composer Ellen Reid is completing the quad-fecta (is that a word?) of premieres by the four major Los Angeles performing arts organizations: in 2018, she’s had new work performed by the LA Chamber Orchestra, the LA Master Chorale, the LA Phil, and now LA Opera. The opera is called p r i s m and it’s a psychological thriller, which employs shifting musical styles and creative uses of space to explore the elasticity of memory following a trauma.