All three of the children found dead in Winden in 1953 and 2019 are wearing the same necklace: a red string with a penny dated 1986. The police in 1953 are completely baffled. The date proves to Ulrich Nielsen that the body belongs to his brother Mads.
Helge and the necklace
In 2019, Ulrich finds a penny on a red string on the nightstand of dementia-stricken Helge Doppler. He takes it with him. Ulrich meets Helge Doppler as a boy in 1953 and gives him the necklace. Doppler keeps the penny for the next 66 years until Ulrich finds it in the nursing home.