A great storm brews out at sea and batters the Devon coast, flooding vast swathes of land. At Wintercombe Abbey the preceding weeks have been spent in a ferment of experimentation, as Jake Wilde's father, David and Maskelyne work furiously on Operation Leah. They have been practising changing tiny events in the past, in preparation for the rescue of Venn's wife Leah from death, the culmination of their work with the Obsidian Mirror. But in the aftermath...

While Jake continues searching for his father and is sent by the obsidian mirror to multiple times in the past, Sarah and Venn battle with Summer for control of a powerful coin.