The suave Count Grendel - Knight of Gracht, Master of the Sword and lord of the Estates of Gracht - resides in Castle Gracht, which is, unsurprisingly, the ancient (and, he likes to claim, inescapable) home of the Grachts. The family's fortunes were tied to a statue on the estate, according to legend. He enjoys typically upper-class diversions and keeps his woods stocked with beasts that would otherwise not be found on the planet Tara, and is the best swordsman on Tara as well. He once had a fling with his chief surgeon and engineer, Madame Lamia, who still pines away for him. But nobility and charm have not made him a pillar of the community - Grendel is second in line for the throne after Prince Reynart, and he intends to be first, through whatever means he must employ.
He plans to marry Princess Strella - the first lady of Tara, a descendant of the Royal House, mistress of the domains of Thorvald, Montgarde and Frayer - and then, once she has become Queen and he King, kill her. When Romana turns up, he is delighted by her resemblance to Strella, for he can use her instead if Strella refuses to co-operate. But Grendel hopes to keep things simpler by simply kidnapping Reynart and trapping him in the dungeon with Strella, for if Reynart is late to his coronation, a new king will be chosen - and Grendel plans to be it. He replaces the palace guard with his own, just to be sure that Reynart stays in the dungeon where he belongs. Thus Grendel's surprise is considerable when, upon entering the throne room for the ceremony, he finds that (an android) Reynart has been smuggled into the throne room through a secret passage and is ready to be crowned king.
With Reynart king, the only thing for it is to assasinate him. Fortunately, Grendel had formed a backup plan for this eventuality as well, creating an android Strella programmed to swear fealty to Reynart and then kill him. His scheme, however, is foiled by the Doctor, so Reynart then has an android copy of Romana made to kill him. The trap is set but the android is destroyed, and when his soldiers start firing, Madame Lamia is caught in the crossfire. Grendel is enraged, partly because he has lost his only servant skilled in building androids. He had hoped to have Lamia make another android Strella which would kill Reynart and then marry Grendel, but with Lamia's death, the android cannot be completed - and as he knows that Strella will not help him, Romana must do so instead. When Romana then escapes, he goes to Reynart's camp ostensibly under a flag of truce, destroys the Reynart android and recaptures her.
Grendel then finds that he must adjust his plans. He decides to force the real Reynart to marry Romana, then kill Reynart and remarry Romana himself. Romana will then die in a tragic accident, leaving him the legal, rightful king of Tara. If Romana refuses to participate, he will kill Strella. But partway through the solemn wedding ceremony, the Doctor interrupts. Grendel duels with him but, finding the Doctor to be a good match for his skills, he decides to forfeit. As Grachts never surrender, Grendel dives off the tower and swims away.
