Martha realizes she's jealous of Rose Tyler when the Doctor takes her on her first adventure. Lying on the bed together, she can't pretend she minds sharing. She has no plans to do anything, of course - she's only just met the man. But she's enjoying herself, nonetheless, until the Doctor ruins it. "Rose would know what to do," he says. And just like that, the moment is gone.

Martha isn't sure exactly what happened to Rose - she's afraid to ask, but she knows it can't be good. She isn't interested in pressing the topic, so she flips off the light and turns away from the Doctor. But she can't help but wonder what would be happening right now if Rose were here in her place. And maybe it's just so that she can help the Doctor, or maybe it's something more, but right now, Martha wishes she were Rose.