question: what is the No in series when Rob wright & Debra j. Fisher & Erica Messer were the writers?
answer: SELECT MIN(no_in_series) FROM table_21313327_1 WHERE written_by = "Rob Wright & Debra J. Fisher & Erica Messer"
context: CREATE TABLE table_21313327_1 (no_in_series INTEGER, written_by VARCHAR)