Yn de lêste winter fan de Twadde Wrâldoarloch moat Izaak syn ûnderdûkplak yn Amsterdam ferlitte, omdat it dêr te gefaarlik wurdt. Hy reizget achter op de fyts by koerierster Els nei syn nije skûlplak, in buorkerij yn it noarden fan Fryslân. En ek al binne de minsken dêr leaf foar him, hy fielt him iensum en ellindich. Pas at er freonskip slút mei it prachtige swarte hynder Hero, feroaret dat. De Dútsers wolle dy sterke Fryske hynst ek graach hawwe, en as de soldaten komme om it hynder op te heljen, kin allinnich Izaak in manier betinke om him te rêden.Martha Attema skreau in prachtich ferhaal, basearre op histoaryske feiten en it boek is twatalich: Frysk/Ingelsk.

During the last winter of World War II, Izaak must leave his hiding place in Amsterdam to travel with Els, a bike courier, to live on a farm in the northern part of the Netherlands. Although the people are kind to him, he is miserable until he makes friends with a beautiful black horse, Hero, a frisian stallion wanted by the Germans. When the Germans come for the horse, only Izaak can think of a way to save him.Martha Attema wrote a beautiful story, based on historical facts, in which truth becomes powerful fiction.