Lethal in Small Doses by David Pearson

Dublin detectives race to track a serial killer targeting care homes. Lethal in Small Doses is the fourth crime fiction title in the Dublin Homicides series by David Pearson.

When an elderly resident of a care home passes away during the night, little is thought of it. But when a routine investigation turns up an anomaly, suspicions are raised. DS Fiona Moore follows her instincts that it is death by foul play and launches a murder inquiry. It is not long before there is a similar death. 

Concerned that they have a serial killer on their hands, DS Moore is nudged off her central role by her boss. Frustrated, but determined to bring the care home killer to justice, she pursues her lines of inquiry. Unfortunately, DS Moore is up against a particularly reckless individual. Having established their identity, if not their motive, the race is on to stop them acting again.