DOCTOR: The Solitract is a frog? Who talks like Grace?

SOLITRACT: My own form is endless, but this frog is a form that delights me, as it once delighted Grace.

YASMIN: For all we know, he took Erik. And now you want us to follow that nutter into the dark?

DOCTOR: No, I want you to follow this nutter into the dark.

GRAHAM: Hey, Doc. Do you think it’s safe?

DOCTOR: I doubt it. It’s a juddering dimensional portal in a mirror in a Norwegian bedroom.