[sufue]

Two first-in-series titles by Peter May are on sale variously at Kindle and Kobo US.

The Blackhouse is the first in the Lewis Trilogy, $2.99. Note that per @Mort1997's earlier post this was free at Kindle UK not too long ago, so check carefully before you buy...
Kindle US: https://www.amazon.com/dp/B00LSX4FUO/
Kobo US: https://www.kobo.com/us/en/ebook/the-blackhouse-3

Spoiler:

From acclaimed author and dramatist Peter May comes the Barry award-winning The Blackhouse, the first book in the Lewis Trilogy--a riveting mystery series set on the Isle of Lewis in Scotland's Outer Hebrides.

When a grisly murder occurs on the Isle of Lewis that bears similarities to a brutal killing on the mainland, Edinburgh detective and native islander Fin Macleod is dispatched to the Outer Hebrides to investigate, embarking at the same time on a voyage into his own troubled past.

As Fin reconnects with the people and places of his tortured childhood, the desolate but beautiful island and its ancient customs once again begin to assert their grip on his psyche. Every step toward solving the case brings Fin closer to a dangerous confrontation with the dark events of the past that shaped--and nearly destroyed--his life.

Extraordinary People, apa Dry Bones, is the first in the Enzo Files, also $2.99.
Kindle US only, not at Kobo US as of now: https://www.amazon.com/Extraordinary...dp/B019WQO4OA/

Spoiler:

Half-Scottish, half-Italian Enzo MacLeod used to be one of the top forensics experts in Scotland, and now he lives in Toulouse, working as a university professor. Divorced in Scotland and widowed in France, he has an estranged Scottish daughter and a French daughter he has raised by himself.

As if his life isn't complicated enough, he soon finds himself unexpectedly in the hunt for solutions to some vexing cold cases thanks to an ill-advised wager about the power of forensic science.

Meanwhile, in Paris, a man desperately seeking sanctuary flees into a church. The next day, his sudden disappearance will make him famous throughout France.

Deep in the catacombs below the City of Light, MacLeod unearths disturbing clues deliberately left behind by a killer. But as the retired forensics expert draws closer to the truth, he discovers he may just wind up the next victim for his troubles.