 The episode is set in the Victorian era and sees the Doctor ( Matt Smith ) brooding with the assistance of Silurian Madame Vastra ( Neve McIntosh ) , her wife Jenny Flint ( Catrin Stewart ) and Sontaran Strax ( Dan Starkey ) , after the loss of companions Amy Pond and Rory Williams in the previous episode , " The Angels Take Manhattan " . He is forced out of hiding to investigate mysterious , sentient snowmen that are building themselves and meets Clara Oswald ( Jenna @-@ Louise Coleman ) , a governess also investigating the snowmen . They discover that the snowmen are being animated by the Great Intelligence ( voice of Ian McKellen ) with the help of a man named Dr Simeon ( Richard E. Grant ) . 
