On the shores of Lake Michigan sits a beautiful stone house. The locals from Sweetwater tell a story about a widow who watched from the window of the house every day of her life, waiting for a promise to be fulfilled. When she died, the house was forgotten for decades, until the Campbell family found it.

Elle and Cole Campbell would like to make the stone house their summer home, but a few things stand in the way. The house needs a renovation, and it's haunted, very haunted.

Cid gets the call to do a PEEPs assessment on the haunted nature of the building. He and Burt ask Kiki Pickles along to assess whether the house is sound and the land safe for the Campbells to live there with their family.

On this assignment, Cid has to wear two hats, the contractor and the ghost hunter, which is challenging enough without continually being mistaken for Emerson, the long-lost husband of the infamous widow, Victoria Buell, who demands that Emerson come home and keep his promise.

The house is waking up and, along with it, the spirits of those killed there, ghosts who possess and ghosts who demand to be heard, no matter the cost to living.

The Promise is the 4th book of the "Cid Garret P.I." series (a spin-off of Alexie Aaron's popular Haunted Series).