Hackers use the state Emergency Communications System to broadcast what they claim to be video footage of dead prison inmates. When MI5 denounces the broadcast as a hoax, terrorists set off a series of false alerts. Mathematician Charlie suspects MI5 activity is related to the London bombing.
| Name | Type | Role | |
|---|---|---|---|
| Howard Overman | Writer | ||
| Michael Keogh | Guest Star | ||
| Everal Walsh | Guest Star | ||
| Melanie Clare | Guest Star | ||
| Parvez Qadir | Guest Star | ||
| Oona Chaplin | Guest Star | ||
| Tom Harper | Guest Star | ||
| Joanne Froggatt | Guest Star | ||
| David Prosho | Guest Star | ||
| Daniel Rigby | Guest Star | ||
| Lorraine Burroughs | Guest Star | ||
| Caroline Harding | Guest Star | ||
| Simon Lawson | Guest Star | ||
| Brendan Maher | Director |