Tang Shiwu accidentally transmigrates to the early days of the Tang dynasty, only to land in Chang'an's prison. Fortunately, he has modern knowledge, so he eats and sleeps well behind bars.
That is, until a somewhat thickheaded young general is imprisoned after taking the blame for a defeat.
What a coincidence! Why don't we swear brotherhood?
Li Er was taken aback. “Swear brotherhood?”
“Sure! Once you get out, recommend me to Li Er as his strategist. Then we can enjoy the good life together, right?”
“I'm a few years older than you, so from now on, you can call me Big Brother, and I'll call you Second Brother!”
“Second Brother, I'm not kidding. With the skills passed down in my family, I can turn you into the Tang dynasty's God of War in no time. Of the twenty-four meritorious officials enshrined in the Lingyan Pavilion, you'll be the first!”