Dr Leonhard hires on as a doctor aboard a cruise ship to follow up on a hot lead that has come up in the missing persons case of his wife Sarah. It involves a photo that shows her at the bar of a ship.

Musical student Clara's big dream is to sing a solo part one day. Clara wants to keep the fact that she is hard of hearing a secret. When Eric finds out about her secret, he realises that Clara urgently needs an operation.

65-year-old Elisabeth is travelling alone on the cruise ship. Her conspicuous behaviour attracts the attention of Captain Henriette Mosbach who suspects dementia and asks Dr Eric Leonhard for support.

Midwife Sybille takes time off on a ship for herself and her baby daughter. When her nose bleeds, Eric takes notice. He diagnoses leukemia and Eric also finds out that Sarah has disembarked on Tenerife.

Lisa is the daughter of Captain Henriette Mosbach. She spends her school vacations on board. During a game, Lisa injures herself in the kitchen and her right hand is almost amputated by a knife.

Passenger Paul is waiting for a saving transplant because of his cystic fibrosis disease. Eric is sent a video of his missing wife Sarah.