When Scotland's leading virologist goes missing Mona and Paterson from the Health Enforcement Team are dispatched to London to find him. In a hot and unwelcoming city Mona has to deal with a boss who isn't speaking to her placate the Professor's over-bearing assistant and outwit the people who will stop at nothing to make sure the academic stays lost. Meanwhile back in Edinburgh Bernard is searching for a missing prostitute while Maitland is trying to keep the Chair of the Parliamentary Virus Committee from finding out quite how untidy the HET office is...