CREATE TABLE table_28561455_1 (no_in_series INT, written_by VARCHAR)

What was the latest episode number that Meredith Averill wrote?
SELECT MAX(no_in_series) FROM table_28561455_1 WHERE written_by = "Meredith Averill"
SELECT MAX("no_in_series") FROM "table_28561455_1" WHERE "Meredith Averill" = "written_by"