example:
<?php //get top level page ID;
$top = ( $post->post_parent ) ? array_pop(get_post_ancestors($post->ID)) : $post->ID;
echo '<ul>';
wp_list_pages('title_li=&child_of=".$top."&depth=1');
echo '</ul>';
?>
example:
<?php //get top level page ID;
$top = ( $post->post_parent ) ? array_pop(get_post_ancestors($post->ID)) : $post->ID;
echo '<ul>';
wp_list_pages('title_li=&child_of=".$top."&depth=1');
echo '</ul>';
?>