Donna and the Doctor take a holiday in the beautiful underwater city of Vallarasee.
Things have changed since the Doctor last swam through. Vallarasee is
now enclosed in an airdome, with Judoon patrolling historic sites. Now,
instead of tourists wearing breathing-helmets, native Fins are forced to
But leaks are trickling into the dome. The Judoon must be persuaded
that disaster is imminent, or thousands will be trapped, as the waters