The release of US academic Xiyue Wang was a bittersweet combination of hope and anger for families of those who have spent years detained in Iran.
Mr Wang was freed from more than three years in jail for alleged espionage after secret talks led to Iranian Prof Massoud Soleimani being released from the US, where he was accused of sanctions breaches.
The release of Mr Wang, which came as a surprise to other families, appears to show how the administration of Donald Trump is prepared to use similar tactics to those of his predecessor Barack Obama to negotiate freedom for citizens.
In 2016, Mr Obama agreed to the release of five US citizens in return for seven Iranian prisoners.
The US also paid $1.7 billion to Iran days later for what it claimed was an unconnected debt repayment from before the 1979 Revolution.
That deal was originally thought to have included Siamak Namazi, a businessman from Dubai, and his father before hopes were dashed.
I am beyond devastated that a second president has left my ailing father Baquer Namazi and brother Siamak Namazi behind as American hostages in Iran in a second swap deal," Babak Namazi said after Mr Wang's release.
“I hope, pray and expect that this is not a one-time trade but the beginning of an expedited process that will bring my family home soon.”
Families are now presenting a united front and lobby for the release of all those held by Iran. They have launched a joint campaign and worked together for submissions to the UN.
The relatives, including Richard Ratcliffe, the British husband of detained charity worker Nazanin Zaghari-Ratcliffe. appeared at an event on Tuesday in the US to highlight the plight of prisoners.
“There was no indication in Washington this week that there was anything imminent, not even a poker-face sign,” Mr Ratcliffe said.
The family of Bob Levinson, a retired FBI agent who went missing in 2007 on Iran’s Kish Island, said they were told on Saturday about the release of Mr Wang by a senior US administration official.
“We are extremely disappointed that US officials were not able to secure Bob Levinson’s release as well, despite all their hard work,” the family said.
“But we know those efforts will continue because they have made his case a priority.
“This release also shows that the Iranian regime knows it must send all the hostages home.”
President Donald Trump said that the US was receiving indications that Mr Levinson was still alive.
“Maybe, very importantly, it shows we can maybe spend a little time with Iran and get something done,” Mr Trump told Miami television station NBC 6. “We are working on it very hard.”
Mr Ratcliffe said the release of Mr Wang was good news but the success of US and Australian governments in securing the release of their citizens highlighted Britain's failure.
He said that officials from the Islamic Revolutionary Guard Corps in 2016 told his wife they were surprised that the UK government had allowed a case involving a mother with a baby to last so long.
Mr Ratcliffe has written an open letter expressing his frustration that UK Prime Minister Boris Johnson has not met him since taking office in July.
While foreign minister, Mr Johnson said no stone would be left unturned in efforts to secure Ms Zaghari-Ratcliffe's return.
“Once the distractions of the elections are out of the way, we will be looking for the government to make good on the PM’s promises," Mr Ratcliffe said.
"They really have deflected their responsibilities for too long."