If Josh called the police, reasoned Sheila, which he would surely do with a deceased ninja on his couch and his fallen comrade stabbed in the kitchen, Sheila knew she would have only two choices: go to jail, or take out one of the police and high-tail it out of there. Sheila liked to believe she was a nice person, and attacking policemen wasn't usually considered a nice thing to do. Then again, jail didn't seem so nice either. So she had only one choice--run for it.
Of course, that could mean trouble for Josh in the form of ninjas, so Sheila quickly jotted down a letter on a discarded post-it note that must have been knocked off the desk in the quick skirmish:
I'm going to Hawaii. Sorry.
OK, so it wasn't exactly a apologetic masterpiece, and "love ya" hardly sufficed for running off to Hawaii, but of course she wouldn't really be in Hawaii--she'd just be laying low for a while. Before she could rethink her decision, she could hear the key being turned in the lock of the front door.
At first she considered jumping out the nearest window, but she didn't fancy acting too "cliched spy heroine," so Sheila decided to just leave via the back door instead. Jumping down from Josh's nice wood patio and giving herself the satisfaction of landing on both her hands and feet, like a cat on an espionage mission, as she would most likely say, she was off...