It has the same concept about the heart transplant. The main lead Tian receives heart transplant from the female lead, because she died in a car crash. Then he felt guilty about her death and decided to go to her workplace (she was a volunteer teacher in a village) and he also becomes a teacher. There he meet the other male lead and he also starts to feel some of the female lead's feelings and eventually ends up with the male lead (It's a BL).

It's also a drama from the insurance theme. The main characters (Hwang Dong Jo and Kim Min Joon have a lot in common). Both of the dramas have the same cool effect of badass main character who is always prepared for everything and have good twists. They are very similar also because there is a revenge theme ( in mad dog is the fact that Min Joon's brother was accused of crashing the plane and in Tracer Dong Joo is trying to find more about his father's death).