Stone Cold: An Agency Christmas
Chautona Havig

When Beryl finds her aunt dead, she flees before the cops blame her. Unfortunately, the killers are after her. Rural Michigan isn’t Gramercy Park, but it does have a great castle to hide out in!
“Gibbs” arrives home from the hospital (broken leg and all) to find someone living on his third floor, hiding out from “goons,” and making boobytraps to fend off an attack!
Beryl is determined to beat the goons at their own game. Gibbs just wants to keep her alive. And maybe steal her heart by Christmas.
A lifetime of Home Alone marathons might just keep Beryl and Gibbs alive.
Stone Cold fits in the series line up as book 6.5 but can be read as a stand-alone with unimportant spoilers for books 3 and 6.