A fun romp which fits really well into the Pertwee/UNIT era.  Tim Treloar is very convincing as the Third Doctor, although I do wish Katy Manning would understand that she sounds more convincingly young when she doesn't try so hard.  The set up - an alien stone spaceship at the bottom of the lake - is a good conceit but the script does end up just jumping back and forth between the ship and dry land for most of episodes 2-4 making it end up a bit repetitive.  It's a good guest cast though which holds the interest and, as someone who wasn't convinced the Third Doctor Adventures would necessarily be for him, as not being a huge fan of that TV era, I do now anticipate more from this series.