Doctor Who: 10 Times The Doctor Was Out Of Their Depth
1. Possessed By Torajii
42 may seem like a pretty run-of-the-mill episode at first glance, but it's got some pretty fascinating moments if you dig a little deeper. One of the most unique aspects of this story is that it's perhaps the only time in the show that the Doctor is legitimately terrified. After venturing onto the S.S. Pentallian's exterior to re-magnetise the jettisoned escape pod in order to save Martha (why is the crucial switch to do that on the outside of the ship, by the way?) the Doctor is possessed by the living sun Torajii, which the ship is imminently going to crash into.
It's a hectic situation as it is, but once the Doctor is infected by the sun, he's completely out of his depth. He's clearly in immense pain as his insides burn with the heat of the sun, and he exhibits genuine fear: "I'm scared, I'm so scared!" David Tennant's impeccable acting really sells the idea that the Doctor has completely lost control. Good thing Martha's close by to help, because he needs it. But the other crew members are working against Martha, cutting the power to the cryo-chamber before she can freeze the Doctor, and soon he is fully possessed, his eyes burning with the sun's light as Torajii gains full control over him. It's rare to see the Doctor so afraid and so helpless -- this might just be the most out of his depth the Doctor has ever been.