Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_29156 ( "No. in series" real, "No. in season" real, "Title" text, "Directed by" text, "Written by" text, "Original air date" text, "U.S. viewers (million)" text )

### Question ###
How many viewers in millions did the Alison McDonald episode get?

### Accurate SQL ###

SELECT "U.S. viewers (million)" FROM table_29156 WHERE "Written by" = 'Alison McDonald'