Error404 redirect to specific folder depending on current page?

[unwashed potato!]

is it possible to redirect a user to index.php of the current folder if they go to a page that doesn't exist?

e.g. if they visit xyz.com/service-one/london.php, they get the page for london as this page exists, but if they visit /service-one/kingston.php (which doesn't exist) it redirects to /service-one/index.php

and then /service-two/kingston.php would redirect to /service-two/index.php

Thanks

 

[unwashed potato!]

cpanel/apache? it's with tsohost