How to check checkboxes in caml query?

In SharePoint 2010 client object model (JavaScript), I am using this caml query to download list items.

There is a column called 'Office' and in it, there are several check boxes (i.e. its a multi-select field). I am looking to get the items where the checkbox in the Office field, that has the name 'Toronto' is checked. I don't want to consider the values of the other checkboxes in the Office field. This query below is not working though because I am getting 0 items, when I know I should be getting more.

    var camlquerystring = "<View><Query><Where><Eq><FieldRef Name='Office'/><Value Type='Boolean'>
    Toronto</Value></Eq></Where><OrderBy><FieldRef Name='Modified' Ascending='FALSE' /></OrderBy></Query></View>";   

Does anyone know what is wrong?

Thanks.