The Return of Hydro-Man: Part 1

S5, E7: Mary Jane and Peter arrive in Niagara Falls for their postponed honeymoon, but it is soon interrupted when Hydro-Man (last seen in season 2) returns and kidnaps Mary Jane, with Spider-Man and the Black Cat in pursuit (she's taking a break from her travels with Blade and Morbius). After some intense detective work, Spider-Man tracks down Hydro-Man to a water factory in New York. Hydro-Man has Spider-Man beat, until someone clobbers Hydro-Man with water powers, and that person is Mary Jane!