During an investigation, Lieutenant Win (Nonkul Chanon Santinatornkul), stumbles across an old two-way radio. To his surprise, it still works, turning on at 23:23, and Win finds himself connected to Captain Yodchai (Krit Shahkrit Yamnam) – but the two soon realize that they're living in different timelines, with Win living in the present day and Yodchai existing in the past. Win and Yodchai discover that they're both detectives, and utilize the radio's ability to share clues across time to help each other with their investigations. With Yodchai's help finding clues in years past, Win is able to solve cold cases in the present and bring closure to victims' families. However, using the present to alter the past has unintended consequences that Win and Yodchai must overcome. The drama is a remake of the 2016 Korean series "Signal."