In 227CE Hadrian's Wall in Britannia, and the brave auxiliary soldiers who man it, provide the physical security for the northern frontier of the mighty Roman Empire. However, only some enlightened few understand the graver supernatural threats lurking among the dark forests and trackless marshes of the border region. Those few are yourselves, the Brotherhood, initiates into the Mysteries of Mithras who serve among the auxiliaries at the Wall. In the past you have saved forts, local villages and some might even say the Pax Romana itself, from dire threats. However, this time it is personal. Members of the Brotherhood of Mithras from elsewhere along the Wall have begun dying in suspiciously icy ways and now your own leader may be in danger.

Summer 1925, and the Season is in full swing among London's socialites. But a strange malaise seems to be sweeping the party-goers. Smythe's Discreet Investigations, London's first all-female detective agency, have been asked to determine whether there is something sinister occurring, or just the usual over-indulgence and late nights common to events involving the Bright Young Things.