What is it?The Help Get Them Home campaign highlights the plight of prisoners, who are often tortured because they have spoken out against the authorities in their countries.
The campaign will be running on rail networks and the London Underground in the coming months, and will also feature in printed publications.
The campaign is designed to encourage commuters in the UK to sign a petition by SMS, demanding the release of three prisoners of conscience in India, Iran and Indonesia.
Anything else happening?
A specially created website sets out the aims of the campaign, explains how the public can get involved and provides details on the three prisoners.
The campaign is being promoted on the charity's Facebook page and Twitter feed using the hashtag #helpgetthemhome.
The actors Vanessa Redgrave and Olivia Colman, the comedian Ed Byrne and the TV presenter Bear Grylls have all been pictured holding a hashtag, which represents prison bars and signifies the relationship between digital action here and the plight of the imprisoned.
Why is the charity doing it?
Amnesty UK director Kate Allen says: "It makes a real difference to people all over the world who are in prison and tortured simply for exercising their rights to free speech or expression to know that they haven’t been forgotten and that there is a global community demanding their release."
Third Sector verdict:
The photographs for this campaign are really effective and will be sure to grab public attention. Encouraging people to text to sign the petition will appeal because they won't have to go online to show their support for the campaign.