When Liz learns from one of her agents that suspicious meetings are taking place at an Islamic bookshop she trusts her instinct that a terrorist cell is at work. Her boss Charles Wetherby Director of Counter Terrorism trusts her as well & immediately puts a surveillance operation into place. An attack seems imminent. So Liz is surprised when Wetherby suddenly takes her off the case. & she's shocked to hear the reason why: he has received a tip-off that a mole is at work inside British Intelligence. If true then the potential damage to the Service itself could be immeasurable. Now as her colleagues scramble to avert a terrorist strike Liz must find out who the mole is & what their intentions are before it is too late.