Hess, the head of a local charity, is launching the country's first "babybox" -- a clean, warm and safe place for a woman to abandon her newborn baby.
"I hear from reliable sources that a woman might come and try and put a newborn baby into the babybox just now," Hess says as he anxiously awaits the first "customer" on 1 June. "Here she comes! She's approaching the wall. The green light is on, she presses the red button, opens the door, and puts the baby in. Now she's hurrying away to retain her anonymity. But that's not all. Now check your watches!"
Less than a minute later, a nurse and doctor respond to a signal sent by the "babybox" and retrieve the infant.
Then he is on his way to a maternity hospital, and within a few weeks -- hopefully -- a new family.
The performance is not the real thing. The "infant" on this occasion is a doll. But the project aims to save real lives.
"I believe that this box behind us will save at least one human life and that we'll no longer have to read stories in the newspapers about newborns being found in rubbish bins," says Hess' colleague, Roman Hanus.
The babybox is a modern solution to an age-old phenomenon. Historically, it was usually hospitals or convents that would accept foundlings, no questions asked.
Hess' babybox is the first of its kind in the Czech Republic, where there are a handful of cases each year of abandoned babies found dead.
Other countries have babyboxes too -- chiefly Austria, Switzerland, and Germany.
Hamburg's SterniPark center was the first to open a "babyklappe" in 2000.
"We believe there are less dead babies found in cities where there are babyboxes," says Jennifer Offenborn, from Hamburg's SterniPark. She says 25 babies have been deposited there in the last five years. And she's convinced the babybox has saved the lives of many.
"In 1999, here in Hamburg, there were found five babies, three of them were dead, two were still alive," Offenborn says. "So we decided to open 'babyklappe' here so that people who [give birth to] their babies at home can put them in there. There are lots of women who get pregnant and no one knows and they don't know what to do. We gave them a chance not to leave their baby somewhere and to put them in the babyklappe. Now in the last five years we found three dead babies, before it was five [in one year]."
But the babyboxes are controversial.
Some German critics opposed them on religious or moral grounds, saying they would encourage more women to act irresponsibly.
Hess' project faced an uphill battle in the Czech Republic, too. He had to choose a private clinic as the Health Ministry is opposed to the plan.
The ministry lists several objections: A babybox would encourage women to give birth without proper medical care. The state cannot support parents' irresponsible actions. Every child has the right to an identity and to know its origins.
And the ministry says mainly foreign and handicapped children are likely to be abandoned in this way -- and handicapped children cost a lot to look after.
"We think that in the Czech Republic, the problem of unwanted pregnancies and the care of unwanted children is dealt with adequately, in contrast to other countries including other EU countries," says Health Ministry spokeswoman Jana Kocova. "Women here are able to get contraception, sterilization, to give birth anonymously. [And] bringing in babyboxes doesn't solve the problem [of discarded babies dying]; these women are acting in the heat of the moment."
But supporters say all these arguments are beside the point.
They say if Prague's new babybox can save even just one life, it will be worth it.