The Secret Revealed
Luthor spoke with his people. He set up teams to track both Superman and Clark Kent. He also had some people check out a woman who seemed to appear each time Superman did. Down below, in the lab, he visited Metallo, who his agents had captured earlier during his fight with the Man of Steel. Luthor removed the Kryptonite that powered him.
The Kent team tranquilized Clark's parents and ransacked their home. They found a scrapbook devoted to averted disasters and Superman. On their way out, a woman saw them. They grabbed her and took her back to Metropolis with them.
Superman noticed a flying device tracking him. He caught it and it self-destructed. Back at his apartment, Clark found bloody footprints leading from his door to a janitor's closet. Inside was Lana Lang - she'd been tortured, but she hadn't given up his secret. Superman found the men who'd snatched her, but Luthor detonated the building. Superman went after Luthor, who admitted he was behind it all. His new Kryptonite ring kept the Man of Steel down.
Superman returned Lana to Smallville and was astonished his parents were still alive (he figured Luthor's people would have killed them). They told him about the stolen items (yearbooks, birth certificate, etc.).
One of Luthor's aides presented him with the conclusion from their data - Clark Kent WAS Superman. Luthor laughed in her face and dismissed it all.
Months later, Luthor had some of his doctors check him out - he was having strange pains in his hand. They found it to be Kryptonite poisoning from the ring. He eventually had to have his hand amputated. He was fitted with a robotic hand.

Certain Death
Luthor dreamed about death while in chemotherapy treatment. In his dream, Superman was the face of the grim reaper.
Superman helped put out a fire at a local brewery.
Luthor decided he would fly the plane he designed - the LexWing - in attempt to set a new world speed record. He ejected his co-pilot over a group of islands. The LexWing later crashed in Peru.
The Daily Planet threw a surprise wedding shower for Lois and Clark. Word of the crash was broadcast; Superman found Luthor's mechanical hand in the wreckage. News outlets began to report his death.

The Ghost of Luthor
Clark told Lois of a dream he'd had - Luthor, as a ghost, threatened him. He left his fiance to check out a nearby disturbance. Some striking taxi drivers were attacking a man for filling in for them. Superman saved him, but as he flew off, one of the men mentioned that nothing had gone right in the city since Luthor died.
Luthor, in death, became a front page news maker - everything from tabloids to national magazines reported on the possibilities of him faking his death. Clark knew otherwise - he'd gathered the remains found at the crash site and they'd been positively identified as Luthor's via DNA testing.
Happersen, one of Luthor's top aides, located his son in Australia. The mother was Dr. Gretchen Kelley, Luthor's personal physician. Twenty-one year old Lex Luthor, II later arrived in Metropolis to take over his father's legacy. ---671---

All this and Lex Luthor II
Superman returned after some time away on the scene of a fire, but he was beaten to it - "Team Luthor," a group of men in mechanical armor, had gotten everyone to safety and the fire was under control. They reported to Captain Sawyer and flew away.
Luthor II had a meeting with Daily Planet management. The paper was operating at a loss, but he promised more revenue even if he had to buy all the advertising space. Perry White, who still held a grudge against the man's father, refused to acknowledge him. He called Lois and Clark and gave them an assignment - find out everything there was to know about Lex Luthor, II.
Luthor soon let one of his rivals within the company know that he was in charge by showing knowledge of a situation only the man and Luthor, Sr. would know. Luthor II promised not to let his secret out.
Superman flew to Australia so he - as Clark Kent - could meet with a colleague who had information on Luthor II. Back in the States, his fiance interviewed the man: he told Lois that he'd found out about his real father after his foster parents were killed in a fire at the age of 16. Lois flipped out and told the boy what a monster his father had been. Luthor II seemed genuinely hurt by the remarks and asked her if she could set up a meeting with him and Superman. Clark's findings in Australia seemed to be in line with what LexCorp had made public.
Superman met him atop the LexCorp building in Metropolis. He shook the man's hand and offered to help put everything that had gone on with his father behind them. Superman gave Luthor a family portrait he'd found in his old burned home. Lex cried when he saw it.
Lois and Clark gave their report to Perry White while Luthor II listened in on the conversation - he'd had White's phone lines tapped.
Markham, the man who Luthor had dirt on, contracted Hellgrammite to kill him.

Man of the Hour
Luthor threw a bash on his yacht - the same one where his father first met Superman. Hellgrammite attacked Luthor after he gave a toast. Superman grabbed the creature and flew him out to sea.
Back in Metropolis, Jimmy witnessed Team Luthor going up against a huge man he called Husque.
After Hellgrammite escaped, Superman headed back to the city to answer Jimmy's signal watch. Lex II was not happy when the headlines showed Superman defeating the monster that Team Luthor could not.
Luthor was called to a crash site in the southwest. Inside the ship was Supergirl. Luthor dismissed his scientists and kissed Supergirl.

In Love and War
Supergirl had mistaken Lex Luthor II for the man (another Lex Luthor) who'd created her on another Earth.
Cat Grant got an interview with the new Luthor. It was to be broadcast live from his home. He used the broadcast to introduce the newest member of the LexCorp team - Supergirl.
Superman visited after the interview and took Supergirl into the sky for a talk. She attacked him when he questioned her judgment. Luthor showed up in a helicopter and broke up their fight. Superman, quite ashamed, flew home and talked it over with Lois.

Talking Heads
Metallo, now in a much larger robotic body, was being carted off after facing defeat at the hands of Superman, but he came back online for another attack. Superman stopped him by pulling off his head.
Luthor had dinner with a woman he described as a business associate. She morphed into Supergirl when a man opened fire on Lex II. The would-be assassin caught one of his own bullets after it ricocheted off Supergirl. She scooped Luthor up and flew off with him.
Sawyer, Turpin, and Superman questioned Metallo hoping to get some information on the mysterious Cerberus. Cerberus had fitted Metallo in the new body and helped free him.
The gunman talked to police. He was a thought-dead geneticist who'd been involved in the plot of preserving Luthor's (the original) brain and implanting it into a cloned body. Cadmus had gained the technology to do so when Brainiac took over LexCorp months previous. Luthor had his filed DNA records altered with that of another man. That man's body was found at the LexWing crash site, thus identified as Luthor. After safely into his new body, Luthor destroyed the Australian facility.
One of the scientist's interrogators stepped forward - it was Luthor.