The Doctor flung open the doors and immediately noticed that something was wrong. "Ummm," Ryan said. "Are you sure this is a small island?"
"Ye... no. Either we came at the wrong place or the wrong time." The Doctor admitted. "Let's check the co-ordinates."
She paused then, "This is the year 9403! This is when the Krillitanes attacked and defeated the forty-third queen of Howlondo and her subjects. Watch out!" she ducked as a long pointy projectile sailed over her head. She closed the TARDIS doors. "Give me a moment, I need to think. So I entered the co-ordinates in correctly..."
Graham looked at the spear and hefted it in his hand. It was light and thin, but strong. He thought The Doc doesn't do weapons, and without a second glance opened the TARDIS door and chucked it out.
There was an angry scream from the direction of its landing point.
The Doctor stopped visibly thinking and gave him a what-did-you-do-that-for-you've-only-made-them-angrier-now-there-will-be-trouble-and-I-don't-mean-me-and-you-that'll-come-later-when-I'm-not-thinking-so-hard-about-this-code glare. That was followed by a make-yourself-useful-and-shut-the-door-behind-you-look-one-of-them-is-trying-to-get-in stare.
He shrugged and grinned, "Just returning it."
Then he slammed the door shut on the bat-like Krillitane's claw. It squealed in pain and flapped off.
"Now, time for some more adventure," The Doctor said. "I figured out the code, at least."
She typed in 4 then 0 then 9 then 3. "Should be the right time and place now," she shrugged.
Crossing her fingers, she opened the door. "Yes! Second time lucky!"
"We're here." Ryan said.
"Yes, you are correct," a Skyu came up to them. "I am Murno Nathia, head commander of the fifth rank. Kilano Mercrit asked me to greet you." She grasped the Doctor's arm firmly and shook it.
"We usually give these to visitors, here," she offered her four purple discs. "These are Capatchi. We only have four, lucky for you. You click them to your arm and they protect our race from your illnesses and germs, and you from ours. If you ever were to take them off, you would succumb to the illness that is spreading round, the Wolfshape."
The Doctor smiled. "Ah, I appreciate that you try to help visitors, but, do these actually work?"
Murno Nathia looked offended, "Why, are you saying our tech is bad?"
"No!" The Doctor raised her hands. "Why would we offend our hosts?"
"Hmmm," said Graham.
"Is this your ship?" Murno Nathia indicated the TARDIS, "It's so small. How do you fit inside it?"
"I... thought I told you last time it was bigger on the inside?"
"Never mind, follow me." Murno Nathia nodded. She turned to lead the way to a row of submarine-like things and then said, "You may have one each. Press this button to switch on the communication and this to start and stop the engine. This is the radar and this is where you each sit. Beware the floor, there, there isn't any. It goes straight from air, to water. Nothing holding the two substances apart. I have to warn you, though, switch your motors off if the radar beeps twice. Understand?"
"I understand," Yaz said.
"I understand," Graham said.
"I understand," Ryan said.
"I don't," The Doctor said.
"What?" Murno Nathia sighed.
"What are the things in the ocean that we have to switch our engines off for?"
Murno Nathia didn't reply. She just pushed the submarines off the edge and into the water.