Three Dog Night is book # 4 in the Mysteries of Cobble Hill Farm fiction series. An invitation to speak at a prominent women's group luncheon prompts Harriet Bailey to reflect on her move to Yorkshire, which makes her miss her family back in the States. Luckily, her aunt Jinny suggests the perfect distraction: attending the village's much-anticipated antiques appraisal festival.

When Ivy, the woman in charge of the event, is found in a nearby cave with no memory of how she got there, she claims to have been confronted by a medieval knight from local legend! Harriet knows this is impossible and is determined to find out what really happened.

As Harriet searches for the mysterious knight's impersonator, more incidents occur, including the theft of a valuable statue and apparent pranks against local businesses. Can Harriet find the culprit before things escalate to a dangerous level?