Lemm arrives on Omega six weeks after beginning his Pilgrimage, looking for exotic adventure, but quickly becomes disillusioned with the station, and leaves. However, while on the planet Kenuk, Lemm encounters two other quarians from the Bavea, a scout ship of the Idenna. They tell him about another scout vessel of the Idenna, the Cyniad, which left to broker a deal and never returned. Lemm becomes interested and decides to go and look for the Cyniad's crew, thinking their safe return might be an appropriate Pilgrimage gift.
The trail leads back to Omega, and, once Lemm has talked--and paid--his way past the batarian patrons at Fortune's Den, to a quarian exile called Golo. He tells Lemm that he brokered the deal but claims not to know what Pel did with the quarians later. Lemm is furious and wants to launch an assault on Pel's warehouse immediately, but settles down and agrees to Golo's suggestion to stake the warehouse out for a few days.
However, Lemm isn't stupid enough to trust Golo implicitly. Though Golo sends a warning to Pel, Lemm attacks the warehouse early, believing he has found four quarian captives who turn out to be Kahlee Sanders, Paul Grayson, his daughter Gillian Grayson and the biotic Hendel Mitra. Lemm rescues them - with the exception of Paul Grayson - as he recognises Kahlee from the quarians' investigations into Saren Arterius.
During the escape, Lemm is shot and badly wounded in the leg, and once patched up by Hendel, has to wear a sealed boot to safeguard himself against infection. Lemm is also forced to leave his shotgun behind in the warehouse; its distinctive quarian modifications provide a clue for Paul Grayson as to who has taken Kahlee, Hendel and his daughter.
Hoping to introduce Kahlee to the Idenna's captain, thereby earning a place on her crew, Lemm agrees to let the three humans hide from Cerberus on the Migrant Fleet, and brings them there in a stolen shuttle. His code phrase - "the quest for knowledge sent me away from my people; now the discovery of wisdom has brought me back" - allows them safe passage aboard the Idenna. While his human friends are quarantined aboard their shuttle, Lemm is allowed onboard the Idenna for treatment. Having brought Kahlee Sanders aboard, the Idenna's captain, Ysin'Mal vas Idenna, permits Lemm to join his crew and the young quarian's name is changed to Lemm'Shal vas Idenna.
When Cerberus attacks the Idenna, Lemm fights on Captain Mal's team disregarding his leg injury, and manages to survive the attack virtually unscathed. By virtue of his determination and courage, despite his age, Lemm is later picked as one of Captain Mal's crew on the Idenna's dangerous five-year mission to leave the Migrant Fleet.
Lemm's last task before they depart is to take Kahlee Sanders and Paul Grayson to the Alliance colony Cuervo, but Grayson manages to escape and stun them both. Lemm wakes up unharmed on Daleon; Kahlee asks him to drop her off at the Ascension Project before he returns to the Idenna and his new crew.