Jo walked into the laboratory with a mug of hot tea in her hands. The Doctor was sitting at the counter performing an experiment on a some sort of sticky green substance. She had no clue what it was, but she was certain she was better off not knowing.

She sat down on a stool next to the Doctor's and started sipping her tea. She filled the Doctor in on the daily news, from the weather to the latest situation the Brigadier was huffing over.

"He does that a lot you, know; huffing," she said, to conclude her message.

"Hmm," the Doctor mumbled. He hadn't taken his eyes off of the green goo. Jo didn't take it personally, of course; he always did this sort of thing. Quite often he wouldn't catch a single word she'd say, but it was still nice to get it off her chest.

Her tea was almost gone now, so she lifted the tea bag up to the brim of the mug to take her final sip. She wasn't thinking about it, so the bag slipped from her fingers and hit her nose. At the same moment Mike Yates walked into the room.

"Ow!" Jo grumbled. She put the mug down and started rubbing her nose.

"Are you alright, Miss Grant?" Yates asked.

"Oh, I'm fine," she replied. "I was just drinking some tea and my tea bag punched me in the nose!"

Yates, trying not to smile, replied, "Why would it do a thing like that?"

The Doctor turned his head away from his experiment for the first time that morning, glancing from Jo, to her tea mug, to Captain Yates. "Evidently it aspires to be a punching bag."

—‑

The following week, U.N.I.T. was being attacked by a large alien resembling a giant mutant‑lizard‑bear. While the Doctor attempted to use various frequencies from his sonic screwdriver to disorientate it, Jo took it upon herself to "save" him, which only resulted in her being picked up and flung around.

"Jo, I was doing quite all right without your help!" The Doctor hollered in her direction. He changed the frequency on his screwdriver and tried to sonic the monster again. No success.

Jo screamed as the monster took a swing at the Doctor with its free arm, sending her flailing in the opposite direction. The Doctor stepped out of the way in time, but poor Jo was getting quite sick to her stomach.

"Doctor, please get me down. I think I'm going to‑" she began. Her sentence was interrupted by a retch, a howl, and a sudden fall to the ground. The monster toppled and the Doctor pulled Jo out of its way.

"Jo, I think you've just saved U.N.I.T.." The Doctor marveled.

"How did I do that?" Jo asked, after the pain in her stomach eased up.

The Doctor paused to think, and after a while a smile appeared on his face. "Jo, it was the acid!" he chuckled.

"The what?"

"The stomach bile from your vomit seems to have had quite an effect on him. I don't suppose you could do that again?"

"What!"

The Doctor sobered and straightened his jacket. "Never mind. I think I have a similar acid in the Tardis."