Heartbeat — Norma Fox Mazer

Tod Ellerbee seems to have what every high school senior wants: good grades, good looks, plans for the future. But Tod knows better than to judge from outward appearances. He has no idea what he will do after graduation, and he can't shake the empty feeling he's had since his mother died.

Tod's also haunted by a promise he made when he was thirteen. When Amos Vaccaro saved his life, Tod vowed to pay him back whenever Amos needed him. Now, four years later, Amos knows what he wants. All Tod has to do is introduce Amos to Hilary Goodman, a girl from Tod's school. How is Tod to know that he'll fall in love with Hilary? And how is Hilary to know she'll fall in love with Tod and Amos?