"Doctor, these readings are starting to scare me," Abi's voice came through the intercom in engineering. The Doctor stopped fiddling with some wires and looked up with a furrowed brow.

"What do you mean?" he called out.

"Well, Korwin's body's changing," she replied. "His whole biological makeup! It's impossible!"

McDonnell jumped up from where she knelling down beside the engine, fear in her eyes. The Doctor stood still, waiting for Abi to speak.

"This is med-centre!" Abi's panicking tone spoke. "Urgent assistance requested! Urgent assistance!"

"Stay here!" the Doctor yelled running out the door. "Keep working!"

Much to his dismay, McDonnell ran after him.

"Urgent assistance!" Abi's voice was quavering.

"Abi, they're on their way," the Doctor heard Erina saying.

As the Doctor and McDonnell tore down the halls, they continued to hear Abi's scared voice over the speakers.

"What's happening to you?" she was saying.

"Burn with me," another voice called out. "Burn-with-me."

From Area 27, Rose and Riley looked up at the speakers, filled with fear on what they had just heard. The Doctor continued running, but skidded to a halt when he heard a voice call out behind him and McDonnell.

"Captain!" Scannell came running up.

"I told you to stay in Engineering!" the Doctor said.

"I only take orders from one person around here," Scannell scowled pushing past him.

"Oh, is he always this cheery?" the Doctor said in a sarcastic tone.

⋆⋆⋆DW⋆⋆⋆

"Elvis," Jackie told Rose through the phone.

"What?" Rose nodded to Riley. "Really, Elvis!"

Riley ran over to the lock machine and began typing in the name. Rose looked up to the speaker as she heard two voices speaking.

"Burn-with-me," what sounded like a man's voice growled.

"Korwin, you're sick!" a woman said breathlessly.

"BURN-WITH-ME."

Door 26 opened with a loud beep and Riley and Rose ran though, only pausing to grab the machine and clamp.

"Mum, you're a star!" Rose told Jackie.

"Of course I am," Jackie said. "Now, we need to have a serious—"

She broke off as a horrible scream came over the speakers, echoing off the metal walls. Rose stopped in her tracks, her heart thudding in her chest.

"What was that?" Jackie yelled.

"I've got to go," Rose whispered and ended the call. She and Riley exchanged nervous glances. Running back over to the intercom, Rose flipped it on.

"Doctor, what were those screams?" She said shakily.

"Concentrate on those doors!" he yelled. "You've got to keep moving forward"

Rose grabbed the magnetic clamp and attached it against the bulkhead. Riley stood by the lock machine waiting for the next question to pop up.

"Impact in twenty seven o' six," the computer counted down.

⋆⋆⋆DW⋆⋆⋆

Scannell, McDonnell, and the Doctor ran into the med-centre. They all looked around franticly for Abi and Korwin, but surprisingly, the room was empty. The stasis chamber lay bare, the slab pulled out with no sign of the Captain's spouse.

"Korwin's gone," McDonnell murmured.

"Oh my god," Scannell whispered and the Doctor turned to see where he was looking. The image of a figure was burnt onto the metal frame of an X-ray machine. The Doctor moved forward toward the silhouette, staring at it carefully.

"Tell me that's not Lerner," Scannell said softly.

"Endothermic vaporization," the Doctor murmured tracing the outline of Abi Lerner. "I've never seen one this ferocious. 'Burn with me.'"

"That's what we heard Korwin say," Scannell turned to McDonnell.

"What?" her voice broke. "You think—? No way, Scannell tell him! Korwin is not a killer! He can't vaporize people! He's human!"

The Doctor moved over to the medical table and picked up the test results. Raising them to the light, he peered at transparencies intently.

"His bioscan results," the Doctor said. "Internal temperature, one hundred degrees! Body oxygen replaced by hydrogen. Your husband hasn't been infected, he's been overwhelmed."

"The test results are wrong!" McDonnell ripped the scans out of the Doctor's hands angrily.

"What is it though?" the Doctor straightened up. "Parasite? Mutagenic virus? Something that needs a host body, but how did it get inside him?"

"Stop talking like he's some kind of experiment!" McDonnell cried.

"Where has the ship been? Have you made planet-fall recently?" the Doctor stared at McDonnell, and she shook her head. "Docked with any other vessels? Any sort of external contact at all?"

"What is this, an interrogation?" McDonnell snapped.

"We've got to stop him before he kills again."

"We're just," the captain took a breath. "A cargo ship."

McDonnell turned away and rubbed her face, keeping back her tears. Scannell glared at the Doctor with a sneer.

"Doctor, if you give her a minute," he muttered going to stand beside her.

"I'm fine," McDonnell breathed. "I need to warn the crew."

The captain went over to the intercom as the Doctor inspected Korwin's lab results. Taking a shaky breath, she alerted her crew of the danger.

"Everybody listen to me," she said. "Something has infected Korwin. We think… He killed Abi Lerner. None of you must go anywhere near him. Is that clear?"

"Understood, Captain," Ashton's voice responded.

"Impact in twenty-four fifty-one."

⋆⋆⋆DW⋆⋆⋆

The Doctor examined Korwin's bioscan results carefully, holding them up to the light for a better look. The whole ship was heating up, getting warmer and warmer as it neared the sun.

"Is the infection permanent?" McDonnell asked from where she sat on a small stool. "Can you cure him?"

"I don't know," the Doctor lied looking down at her.

"Don't lie to me, Doctor," McDonnell saw right through him. "Eleven years we've been married. Chose this ship together. He keeps me honest, so I don't want false hope."

"The parasite's too aggressive," the Doctor muttered. "You're husband's gone. There's no way back. I'm sorry."

"Thank you," McDonnell's voice was not above a whisper. She lowered her head sadly and the Doctor looked away.

"Are you certain nothing happened to provoke this?" he asked. "Nobody's working on anything secret? 'Cause it's vital that you tell me."

"I know every inch of this ship," the captain said. "I know every detail of my crew's lives. There is nothing."

"Then why is this thing so interested in you," the Doctor narrowed his eyes. McDonnell looked away and shook her head softly.

"I wish I knew," she whispered.