Improbable Mission

The Disaster continues to slam into 15th Century Earths. Only a small percentage of the Multiverse is affected, but that still means a myriad of Earths with entire populations slaughtered. Lord Ox's concubine Ragnhild wants to make rescue a business and why not if it means more people get rescued? Time travelers can easily rescue people, but what do you do with them once you rescue them? And how many twins does a person need?