A place of safety - Natasha Cooper

Trish Maguire is blessed with a slug of unexpected free time when a big case settles before it gets to court. She plans to spend it with her family. Sir Henry Buxford, an influential acquaintance, has other ideas. He asks her to investigate one of his private charities, a magnificent art collection built up before 1914 and lost for most of the twentieth century.
The work is right outside Trish's usual field, and she needs all the time she can get to help her 9-year-old half-brother adjust to life after his mother's violent murder. Only Buxford's passionate desire to protect the vulnerable people involved in the Gregory Bequest Collection persuades her to take on the job.
Giving herself a crash course in the murkier end of the art market and learning more than she can bear about the suffering in the trenches during the First World War, Trish soon finds herself sharing all his concern. As the small job grows to monster proportions, invading her professional and private lives, it brings about a death she knows she will never forget.