How to use plugin pages without a menu entry

I’m writing a plugin and most of my plugin pages are accessed from a menu item, I’m using add_menu_page and add_submenu_page. All of these pages work fine.

However I have another page that I don’t want accessed via a menu. The user has to select an item from one of the plugin pages then press a button and they will be taken to this other page. The problem is I get the message “You do not have sufficient permissions to access this page”. If I add an add_submenu_page for this other page it works fine but I don’t want it be accessible directly via a menu option.

Is there another way to make this page viewable without having to declare it as a menu item?