filtering dataframe by value, new df gives "Keyerror: True"

Question

I have an excel file with data like this:

employee      id       department
Jane Smith    12345    HR
Joe Smith     54321    IT
Lee Smith     52341    Admin

I create a dataframe like so:

df=pd.read_excel(filename)

I am trying to create a new dataframe of just the people in one department.

admin_folk = df[df['department'].str.contains('Admin').any()]

What I get is "KeyError: True"

Every post I see on filtering out dataframes by value use the above construct. I know that the construct returns a Boolean value, but I thought creating a new df carries all of the values for that row.

What am I doing wrong? Thanks