"Returning this week is Alex Kingston, who, of course, plays the Doctor’s wife, Professor River Song. It is clear that Kingston plays River with much more maturity and she is not too dissimilar to the River we see in “Forest of the Dead”. However, River also reveals the flirtatious side to her character in a few amusing scenes with the Doctor. The character of River is used very well in this episode and she is also given a well-deserved screen time of at least 30 minutes. Her character also shows that she knows more about the Doctor than himself as is evident in a scene where she says to the Doctor, “This is what is important: Don’t travel alone!"