"No evidence," Sara muttered from over Grissom's shoulder.

The two of them were investigating a murder that took place in an airplane. Several people beat up a man because they assumed he was going to take down the plane when they heard strange noises coming from a lavatory that he stepped out of several minutes later.

"Well, there's no patent evidence, but if there's blood present, there should be latent evidence," Grissom replied, clicking off the flashlight he had been using.

Sara grabbed a portable ultraviolet light from the kit and handed it to him, smirking. "One step ahead of you, every so often."

He smiled. "Thank you."

Taking the light, he clicked it on and crouched in the narrow space, fully aware of Sara, who was watching his every move like a hawk, standing behind him. He slowly scanned the light over the toilet, but then paused. "Would you please get me the portable light microscope from my field kit?"

Sara did as she was asked, handing him a cone-like microscope with a long, thin flashlight pointing down to where the specimen would be observed.

He positioned the ultraviolet light carefully next to him, then began peering through the microscope.

"I take it that's not blood?" Sara questioned after a moment.

"No, but there's protein in it," he replied.

It took Sara a minute to understand what he meant. "Oh, the Mile High Club!" She chuckled, using the slang term for having sex in an airplane's lavatory. "That means the passengers may have had no idea what was going on inside that cabin."

"High altitude is said to enhance the sexual experience. It increases the euphoria." He replied.

"Well, it's good," Sara said after a moment. "I don't know if it's that good."

Grissom paused, and turned to gawk at her skeptically.

"Cite your source," she said, trying to hide her blush.

"Would you hand me a swab, please?" he said abruptly.

"You're avoiding the question!" Sara retorted, grinning wickedly. "'Enhances sexual experience; increases euphoria,'" she quoted. "Cite your source."

"A magazine." He said finally.

"What magazine." She prompted, narrowing her eyes playfully.

"Applied Psychodynamics in Forensic Science."

"Never heard of it."

"I'll get you a subscription."

She and Grissom were staring each other down. "Cite your source." Grissom said after a moment.

"Oh, now you want to go down that route?" She could feel the blush returning to her face."

"Yeah." he responded unwaveringly.

She offered him an apologetic smile. "Uh, never mind."

"Hey, you started it." He reminded her. He lowered his glasses and peered at her over them, giving her "The Look".

She sighed. It was hopeless. She turned her head away so she wouldn't have to make eye contact with him. "Delta Airlines." She said finally. "Flight 1109. Boston-Miami. March 1993. Ken Fuller. Hazel eyes. Organic Chem Lab TA. BMOC. Overrated... in every aspect."

She turned to him. His jaw had dropped, and he was staring at her with a disbelieving expression.

"Can we, um, get back to work please?" She shifted uncomfortably when her voice cracked, adding to her embarrassment.

"Um... yeah..." Grissom said finally. But a small smirk was on his lips as he added "But I think that due to your...uh, first-hand knowledge and experience in airplane bathrooms, you should do the test."

Sara gaped at him. He did not just do that! "Fine," she shot back, and was further embarrassed when her voice cracked again. She ducked her head and grinned. Grissom laughed.

a/n: Last chapter for today. :P