Ten little herrings - L. C. Tyler

When obscure crime writer Ethelred Tressider vanishes, his dogged literary agent, Elsie Thirkettle, is soon on his trail. Finding him (in a ramshackle hotel in the French Loire) proves surprisingly easy. Bringing him home is more difficult. Who would have predicted that in a hotel full of stamp collectors, the guests would suddenly start murdering one another? Elsie is torn between her desire to interfere in the police investigation and her urgent need to escape the town's chocolaterie, but finally the time comes when she must assemble the suspects in the Dining Room, and reveal the truth...