Sam learns that an operation is to be conducted on him in 2006 to try and revive him from his coma. However, he believes that to return to the twenty-first century, he has to betray his colleagues in 1973 — but can he regard them as imaginary, or are they real - at least for him?

• John Simm
• Philip Glenister
• Liz White
• Dean Andrews
• Marshall Lancaster
• Noreen Kershaw