As temperatures soar across Europe during the hottest summer for 40 years, a series of hoax terrorist attacks is generating panic in London. Then a bus blows up on Oxford Street and the hoaxes have suddenly become real.

Student Brioni O'Brien has been desperately trying to contact her older sister since she unexpectedly returned early from travelling, so when Marissa’s bag is found near the site of the explosion, she fears the worst.

Teaming up with terrorism expert Anna Lockharte to search for Marissa, Brioni discovers that her sister got herself into a very dangerous situation - and now she and Anna could be caught in the fallout.