Prince Albert is sent as king’s messenger to a foreign country on an important diplomatic mission, and carries with him some very valuable documents. Some anarchists having heard of this voyage of the Prince, plot to assassinate him, and bribe one of his servants to furnish them with the particulars of the contemplated journey. This servant overhears a conversation between the Prince and his accompanying staff of detectives, and according to this news, the anarchists manage to board the steamer Slavonia, on which the Prince is to travel. Hidden in a large packing case, in which they were smuggled on hoard, they escape the observation of any of the officers or crew. The only one who is suspicious of the case is the wireless operator, and he calls the attention of the captain to it, but is not listened to. The anarchists have little difficulty in prowling around the steamer, and in placing their infernal machine, which is regulated to blow up the steamer at a certain hour, so as to give them plenty of time to escape the disaster. In the meantime, however, the police on shore happen to hear of the affair, and arrest the servant, who confesses everything. With the aid of the wireless telegraph, a message is sent out to sea, informing the captain of the news. But the difficulty for the captain is to find the place where the machine is placed, and he is now vexed that he did not listen to the advice of the wireless operator. In feverish haste the whole boat is searched, during which time the anarchists take advantage of the excitement and escape in a small boat, and now can be seen in the distance from the ship. A number of the crew volunteer to give chase, and a boat is lowered and the race commences between the two boats. The crew’s boat finally succeeds in catching up with the anarchists, and after an exciting combat the anarchists are taken prisoners. On their return to the steamer, they are at pistol’s point forced to tell where they have concealed the infernal machine and the time of the explosion. The wireless operator is in an almost exhausted condition after the search, but he fearlessly picks up the bomb and throws it overboard, after which the strain proves too much for him and he sinks to the deck unconscious. He soon recovers, however, and is handsomely rewarded by the Prince for his pluckiness.