Surrounded by heavily armed police, the four defendants - three citizens and one resident of Sweden - were led in handcuffs into the media-packed courtroom just outside the capital of Copenhagen, where they will be accused of terrorism and illegal possession of weaponry.
The men - Munir Awad, Omar Abdalla Aboelazm, Mounir Ben Mohamed Dhahri and Sabhi Ben Mohamed Zalouti - could face some 16 years in prison if found guilty, while prosecutors were expected to ask that the men be deported from Denmark after serving their sentence.
Henrik Stagetorn, a lawyer for Dhahri, the Swedish resident, told The Associated Press before the trial that his client would plea guilty to the weapons violation but not guilty to the terrorism charge.
The other three were likely to plea not guilty to both the terrorism and weapons accusations.
Three of the four defendants were arrested in December 2010 while allegedly on their way to carry out a violent shooting attack on the Jyllands-Posten newspaper that published 12 cartoons of the prophet in 2005.
The fourth, Sabhi Ben Mohamed Zalouti, left the car while it was en route and returned to Stockholm, where he was arrested the same day as the others.
Swedish security police had been monitoring the group for months. After the arrest Danish security officials described the men as "militant Islamists with relations to international terror networks."
News of the group's alleged attack plans sent a tremor through the largely peaceful Danish society, which is attempting to lay to rest the 2005 cartoon debacle.
Early in 2011 a Danish court declared a Somali man guilty of terrorism for breaking into the home of a Danish cartoonist who had caricatured the Prophet. Wielding an ax, the man entered Kurt Westergaard's home in the northwestern town of Aarhus, though the cartoonist managed to avoid injury by locking himself inside a panic room.
The Somali man was eventually sentenced to nine years in prison.
The new trial will last approximately two months, with a verdict expected in mid-June.