Purloined Poinsettia by Dahlia Donovan

Murder comes knocking when a killer hunts for budding amateur detective Pineapple “Motts” Mottley in the fourth novel of the Motts Cold Case Mystery series.
The past and present collide for Motts when two serial killer brothers barge into her plans for Christmas in London. Her desire to solve her childhood friend’s murder brings her ever closer to danger. She finds herself one fall away from the grave herself.
When one of her former primary school teachers winds up dead in her burning house, Motts realizes the mystery is far more twisted than she ever imagined.
Is she running out of time to catch not one but two killers?
What sort of macabre gift will Motts find wrapped under the tree?