Two mysteries collide: the USS Hood answers a distress call from the decades-lost Roger Korby expedition, while light-years away Kirk's shore leave on Tranquility Seven spirals into mistaken identity, mayhem, and murder once an android duplicate slips into his place and starts giving orders on the Enterprise's bridge. Friedman's sequel to the android-duplicate episode "What Are Little Girls Made Of?" asks what happens when both timelines catch up with the real Kirk at once.
Summary by Loreful, from public sources