Liz Shaw - Caroline John
Dr. O'Kane - Jon Pertwee
Dr. Dove - Sylvester McCoy
Russell - Colin Baker
Bayliss - Linda Lusardi
Patient Zero - David Terence
Dr. Bruffin - Mark Gatiss
Dr. Hearst - Nicola Fulljames
Haggard - Louise Jameson
Dr. Gilchrist - Patricia Merrick
Cummings - Jonathan Rigby
P.R.O. - Sophie Aldred
Orderly - Simon Messingham
Orderly - Alexander Kirk
Daniel - Bill Baggs
Boy's Voice - Daniel Mills
Patient One - Peter Davison
D.I. Burke - Terry Malloy